4.4 Requirements register (normative)

Generated from data/requirements.json by tools/requirements.py. Do not edit by hand.

Each row is one requirement: its identifier, the product types it applies to in a claim and the condition that brings it in, its text, how it is verified (Annex A gives the methods), and why it exists. Rows are grouped by the part they are written in. Every product owes the rows of Part 2, Core; a product owes the rows of an optional interface of Part 3 where it has it; Part 4 binds the installer. A row with a bracket applies only to a product that has what the bracket names, such as a PWR-BUS entry or a COAX-IN, which its claim file shows. The register and the data models are the specification; the clause pages and the PDF render them, and a mismatch in a rendering is an error in the rendering. Each row's provenance (quoted, inherited, measured, calculated, or EIS) and the roles and interfaces it binds are recorded in data/requirements.json. Roles, interfaces, and product types are defined in Conformance. Clause prose cites identifiers without the EIS- prefix. From the first tagged edition an identifier is never reused, and a requirement whose meaning changes gets a new one.

Product type	Core	Optional interfaces
module	52 shall, 1 may	23 shall
enclosure	30 shall	23 shall
bus board	20 shall, 3 may	23 shall
power supply	29 shall, 1 may	11 shall
cable	6 shall	4 shall

Chapter 9 binds the person assembling a system, not a product: 9 rows.

Part 2 Core

5.1 Rack dimensions

ID	Applies to	Requirement	Verified by	Why
EIS-RACK-001	module, enclosure	One HP shall be 5.08 mm.	inspection	Every width in a row is a multiple of the HP, so quoting the IEC value lets panels and rails from different makers line up hole for hole.
EIS-RACK-002	module, enclosure	One rack unit shall be 44.45 mm.	inspection	The rack unit sets the 3U and 1U heights that panels, rails, and 19-inch rack frames share, so quoting IEC keeps them all on one grid.
EIS-RACK-003	enclosure	A rack-mount frame shall meet IEC 60297-3-101:2004 and IEC 60297-3-100:2008 for the flange width, flange mounting-hole positions and slot, the 3U height H1, and the 84 HP row width.	inspection	Meeting the IEC flange, tab, height, and row figures lets a rack-mount frame bolt into any 19-inch rack and hold a full 84 HP row.

5.2 Modules

ID	Applies to	Requirement	Verified by	Why
EIS-PANEL-001	module	A module shall be 1U or 3U high.	inspection	These are the only two panel heights EIS defines; a module of any other height fits no conforming row.
EIS-PANEL-002	module	An N HP panel shall be no wider than N × 5.08 mm, where N is a positive whole number.	inspection	A panel at or under its nominal width lets neighbors sit side by side without binding, so N HP of panels always fits an N HP row.
EIS-PANEL-003	module	A module shall publish its width in HP and how far it extends behind the panel's back face.	inspection	A buyer compares these two figures with a row's published width and clear depth to know the module fits before buying it.
EIS-PANEL-004	module	A front panel shall be no more than 2.0 mm thick.	inspection	The mounting-screw length window is computed for panels up to 2.0 mm; a thicker panel leaves too few threads engaged in the insert.
EIS-PANEL-005	module	A patch jack shall be a 3.5 mm mono (TS) socket.	inspection	One patch connector across all modules means any patch cable joins any output to any input, whoever made the modules.
EIS-PANEL-006	module	A 3U front panel shall be 128.5 mm high.	inspection	128.5 mm is three rack units (133.35 mm) less 4.85 mm, which fits the panel inside the IEC 3U height H1 of 132.55 mm.
EIS-PANEL-007	module	A 1U front panel shall be 39.65 mm high.	inspection	39.65 mm, one rack unit less 4.80 mm, is the Intellijel 1U panel height, so 1U modules fit the 1U rows already in use.
EIS-PANEL-008	module	Mounting holes shall be 3.0 mm in from the top and bottom panel edges.	inspection	A fixed inset from each edge puts every panel's holes on the same line as the rail inserts, whatever the maker.
EIS-PANEL-009	module, enclosure	The mounting-hole span, on the panel and between the inserts of a row's two rails, shall be 122.5 mm at 3U and 33.65 mm at 1U.	analysis	The span is the panel height less twice the 3.0 mm inset, and the rails must match it or the panel holes miss the inserts.
EIS-PANEL-010	module	Mounting holes shall be drilled Ø3.2 mm, or slotted 3.2 mm wide and no longer than 5.5 mm along the rail, centered on the hole position.	inspection	A 3.2 mm hole clears the 3.0 mm M3 screw with room for small position errors between panel and insert; a short slot along the rail takes up rail position error without letting the panel drop.
EIS-PANEL-011	module	Each mounting hole shall be a whole number of HP plus 2.54 mm from the panel's nominal left edge.	analysis	Offsetting holes by half an HP from the nominal edge puts every hole on an insert hole, whatever the panel width and wherever it sits.
EIS-PANEL-012	module, enclosure	A board shall stay at least 9.25 mm clear of the top and bottom panel edges, and a rail shall cover no more than 9.25 mm of the panel face at each edge.	inspection	(128.5 mm − 110 mm) / 2 is 9.25 mm, so the usual 110 mm board fits between rails that cover no more of the panel.
EIS-PANEL-013	module, enclosure	A dimension of clauses 5.1 to 5.3 shall hold within the tolerance the register states for its requirement; a dimension with no tolerance stated is a limit.	measurement: each dimension of clauses 5.2 and 5.3 against its tolerance or limit	A nominal figure without a tolerance cannot be checked or rejected; one policy makes every mechanical figure measurable the same way.
EIS-PANEL-014	module	A front panel thinner than 1.6 mm shall ship with M3 mounting screws with a head at most 7.0 mm across, whose length fits the window of clause 5.3 for its own thickness on a rail of the section clause 5.3 recommends.	inspection	The screw length window (RAIL-009) keeps the tip off the cavity floor only through a panel 1.6 mm or thicker; through a thinner one an enclosure's screws can bottom out, so the panel brings its own.
EIS-PANEL-015	module	A module shall publish whether its front panel is connected to its 0 V, and whether the panel is bonded to the rails.	inspection	A panel at 0 V that is also bonded to the rails is a second chassis tie, and a panel that touches its neighbors joins two modules' 0 V; the installer can only avoid the loop if each module says what its panel is.

5.3 Rails, inserts, and mounting screws

ID	Applies to	Requirement	Verified by	Why
EIS-RAIL-001	enclosure	The holes in a rail insert shall be 5.08 mm apart.	analysis	Insert holes one HP apart line up with panel holes placed on the HP grid, so a panel screws down at any position in the row.
EIS-RAIL-002	enclosure	A rail for an N HP row shall give at least N × 5.08 mm of mounting length.	analysis	N panels at their full nominal width need N × 5.08 mm of rail, so a shorter rail cannot hold the row's published width.
EIS-RAIL-003	enclosure	An insert shall be threaded M3.	analysis	The insert thread has to take the M3 mounting screw that every module hole is drilled to clear.
EIS-RAIL-004	enclosure	An insert shall be at least 1.5 mm thick, three thread pitches.	analysis	An insert three 0.5 mm pitches thick gives the screw the three full threads RAIL-008 needs to hold a panel without stripping.
EIS-RAIL-005	enclosure	A mounting screw shall be M3.	inspection	M3 is the thread of nearly every Eurorack case on sale and of the screws modules ship with, so one screw fits any row.
EIS-RAIL-006	enclosure	A mounting screw's thread pitch shall be 0.5 mm.	inspection	Quoting the ISO 261 coarse pitch means any off-the-shelf M3 screw threads into any conforming insert.
EIS-RAIL-007	enclosure	A mounting screw's major diameter shall be 3.0 mm.	inspection	Quoting the ISO 261 diameter fixes the size that the 3.2 mm panel hole and the rail throat are made to clear.
EIS-RAIL-008	enclosure	A mounting screw shall engage at least three full threads through a 2.0 mm panel.	inspection	Three engaged threads through the thickest allowed panel keep a screw from stripping out as cables are plugged and pulled.
EIS-RAIL-009	enclosure	The mounting-screw length L shall satisfy 2.0 mm + seat + 1.5 mm ≤ L ≤ 1.6 mm + D, with seat and D measured behind the rail's mounting face. The throat in front of the insert shall clear 3.0 mm.	analysis	The lower bound gives three threads through a 2.0 mm panel, and the upper keeps the tip off the cavity floor through a 1.6 mm panel.
EIS-RAIL-010	enclosure	The mounting-screw head shall be at most 7.0 mm across.	analysis	The narrowest catalog rail face reaches 3.7 mm past the hole center (the Vector T-strut, half its 7.391 mm height), so a head up to 7.0 mm across bears on panel and rail face on every catalog rail; an ISO 7045 pan head and the common 7 mm M3 washer fit.
EIS-RAIL-011	enclosure	An enclosure shall publish the mounting-screw length, and shall supply those screws or name them.	inspection	The right screw length depends on the rail's seat and cavity depth, which only the enclosure maker knows.

5.4 Enclosures

ID	Applies to	Requirement	Verified by	Why
EIS-ENC-001	enclosure	An enclosure shall publish, for each row, its width in HP and the depth it keeps clear behind the panel's back face.	inspection	A buyer compares these figures with a module's published width and depth to know it fits the row before buying.

6.1 Power architecture

ID	Applies to	Requirement	Verified by	Why
EIS-PWR-001	module, power supply, bus board, enclosure	A product shall publish, for each power entry, the maximum current it takes on each rail at the entry's nominal voltage, stating 0 for a rail it does not draw.	inspection	An installer sums these figures against the ratings of the source and of each product with outlets (ASM-001), and a buyer sizes a DC adapter from them; a stated 0 shows a rail was not forgotten.
EIS-PWR-002	module, power supply, bus board, enclosure	A power supply, a bus board, and any product with power outlets shall publish the maximum current it delivers on each rail, in total and at each outlet.	inspection	An installer checks a row's summed currents against the source total and each outlet before adding a module (ASM-001); an outlet can be rated below its rail, and an overloaded trace or connector overheats.
EIS-PWR-003	module, power supply	A product whose power entries are alternatives, each able to power it alone, shall not require more than one of them to be connected at the same time.	inspection	The installer connects only one of a product's alternative sources (ASM-003), so the product has to run from any one of them alone; entries that feed different circuits, such as a DC entry for one board and the bus for another, are not alternatives.
EIS-PWR-004	module	A module shall not source current into a rail of any of its power entries.	inspection	A module that drives a rail fights its source's regulator and can back-power other products when the source is off.
EIS-PWR-005	module, power supply, bus board, enclosure	Where a product takes or gives a rail or 0 V on row wiring, the discrete conductors between a power supply, a bus board, a DC entry, and PWR-DC12 outlets, each terminal shall be an M4 screw, stud, or threaded standoff that clamps a ring terminal under a lock washer, rated for at least the current it carries, and the product shall publish the conductor sizes its terminals accept.	inspection	One terminal on every supply, bus board, and DC entry means one ring terminal and one crimp tool for any pair of makers; a bolted ring does not work loose as a push-on tab can, and M4 is the ring the trade stocks from 22 to 10 AWG.
EIS-PWR-006	module, power supply, bus board, enclosure	A row wiring conductor shall be insulated stranded copper rated 105 °C or more, with a crimped ring terminal at each end, of at least 18 AWG (16 AWG above 3 A, 14 AWG above 5 A, 12 AWG above 8 A, 10 AWG above 15 A), and shall carry no more than 25 A; a 0 V conductor carries the larger of the +12 V and +5 V currents together and the −12 V current. A joint shall not rely on solder alone. A 0 V link may instead be a tinned copper braid with crimped or pressed ring ends, or a copper bar, of no more resistance.	inspection	The gauges keep a conductor's heating small in a closed case, the temperature rating suits one, and a crimp holds where a soldered strand fractures; above 25 A a second pair shares the current.
EIS-PWR-007	module, power supply, bus board, enclosure	Each row wiring conductor shall measure no more than 5 mΩ from ring terminal to ring terminal, and the 0 V conductor between a power supply and a bus board, or between linked bus boards, no more than any rail conductor beside it.	measurement: four-wire resistance of each conductor at 20 to 25 °C, ring terminal to ring terminal; or its gauge and length within the row wiring table of 6.1	Every module in a row returns its current through the row wiring's 0 V, so its resistance couples each module's current into every other module's reference; Hinton Instruments sets 5 mΩ for supply cables for that reason.
EIS-PWR-008	module, power supply, bus board, enclosure	Where a product bonds its 0 V to its chassis or to a protective-earth terminal, the bond shall be a conductor of at least 14 AWG, or copper of its own board of that section, landed by a ring terminal, a bracket, or a standoff on an M4 or larger stud or screw that presses metal GND-004 accepts under a toothed lock washer, or a bus bar of equivalent section.	inspection	A bond through paint or a loose terminal is a bond only until it corrodes; a toothed washer on metal that conducts keeps it low impedance for the life of the case, whether the bond arrives on a wire or on the board's own copper.

6.2 Power supplies

ID	Applies to	Requirement	Verified by	Why
EIS-SUP-001	power supply	A power supply shall publish its ripple and noise on each rail it provides, peak-to-peak, measured as stated in clause 6.2.	measurement: ripple and noise per rail, peak-to-peak, by the 6.2 method	A ripple figure taken one stated way lets a buyer compare supplies and pick a quiet one for video or audio work.
EIS-SUP-002	power supply	A power-supply output on a plug-and-socket connector other than a power header shall not mate with reversed polarity; a power-header outlet meets the marking and keying of clause 6.4 instead.	inspection	A supply connected backwards reverses every rail on the bus and can damage every module in the row at once.
EIS-SUP-003	power supply	A power-supply output on row wiring terminals shall mark each terminal with its rail or 0 V.	inspection	Ring terminals on studs cannot be keyed, so a clear marking is the only guard against wiring a rail to the wrong place.
EIS-SUP-004	power supply	Each output rail of a power supply shall survive an indefinite short to 0 V without damage, and shall return to its rated output when the short is removed, after an input cycle if it latches off.	measurement: each rail shorted to 0 V for at least 1 h, one rail at a time, then the short removed: no damage, and the rail returns to its rating	A short from a miswired ribbon or bus board is a routine fault, and the supply has to outlast it until someone finds it.
EIS-SUP-005	power supply	During power-up, power-down, or a short on another rail, no output rail of a power supply shall be driven more than 0.7 V toward the opposite polarity.	measurement: each rail's swing past 0 V, at power-up, at power-down, and with the other rail shorted to 0 V, with a resistive load between +12 V and −12 V drawing the smaller rail's rated current	A rail pulled past 0 V reverse-biases every module's decoupling and the substrate of every IC on it; 0.7 V is a silicon diode's drop at modest current, and a Schottky clamp across each rail holds it at rated current.
EIS-SUP-006	power supply	At start-up, no output rail of a power supply shall overshoot its nominal voltage by more than 10 %.	measurement: overshoot of each rail at start-up, at most 10 % of nominal	Parts on modules are chosen for the rails they run from, and a large start-up overshoot eats the voltage margin they were sized with.
EIS-SUP-007	power supply	Each output rail of a power supply shall have ripple and noise below the limit tabulated in clause 6.2 for its power interface, 150 mV peak-to-peak on PWR-BUS, measured as clause 6.2 states.	measurement: ripple and noise per rail below the limit of its power interface, by the 6.2 method	A 150 mV ceiling gives modules a worst case to design against, at a level most open-frame switching supplies already meet.
EIS-SUP-010	power supply	Each output rail of a power supply shall stay within ±5 % of its nominal voltage at its output terminals, from the minimum load the supply publishes on each rail to its rated current, whatever the load on its other rails within those limits.	measurement: each rail's voltage at its output terminals at its published minimum load and at its rated current, with the other rails at each end of theirs	A module's regulators, references, and patch levels are designed for ±12 V and +5 V; a rail 10 % off conforms to nothing else in EIS, and a cross-regulated supply drifts that far when one rail is lightly loaded.
EIS-SUP-008	power supply	A power supply mounted on the product it powers shall publish the heat it dissipates at its rated output and how far it extends behind that product.	inspection	A linear regulator turns the difference between its input and output into heat in the case, and it adds to the depth of the module it sits behind; the installer budgets both (Annex H, ENC-001).
EIS-SUP-009	power supply	A power supply may provide the 12 V DC rail of clause 8.1 alongside or instead of the bus; it then has PWR-DC12 outlets, publishes the current of each outlet, and meets the outlet rules of clause 8.1.	inspection	A case supply that gives a DC rail directly saves a brick per module, and its outlets keep the rules of 8.1 like any other PWR-DC12 outlet.

6.3 Grounding and 0 V

ID	Applies to	Requirement	Verified by	Why
EIS-GND-001	module, power supply, bus board, enclosure	A product shall connect every 0 V pin of its power headers, and the −V of its DC entry, to its 0 V.	inspection	The 0 V pins share the return current of all three bus rails, and using only some crowds it onto fewer contacts; with the DC rail's −V on the same 0 V, a product keeps one reference for its signals whichever entry is connected.
EIS-GND-002	bus board	A bus board shall join the 0 V pins of every header to one 0 V that runs to the supply's 0 V terminal.	inspection	One 0 V back to the supply terminal gives every module in the row the same reference and a defined path for return current.
EIS-GND-003	power supply	A power supply shall publish whether its 0 V output is connected to protective earth, and where.	inspection	A system wants one bond between 0 V and protective earth; a second bond lets mains-frequency current flow in 0 V as hum.
EIS-GND-004	module, power supply, bus board, enclosure	Where a product makes a bond of a metal part to its 0 V, to its CHASSIS terminal, or to another metal part, and publishes it as a bond, the fastener shall press bare, plated, or conversion-coated metal, or a copper land clear of solder mask, not paint, powder coat, anodizing, or solder mask, and the bond shall measure at most 100 mΩ, and a bond of 0 V to the chassis (PWR-008) at most 10 mΩ.	measurement: four-wire resistance at 1 A or more between the two parts, after assembly; this does not replace the protective-bonding test of the safety standard a mains product is certified to	A finish either conducts under a fastener, at a few milliohms, or is a dielectric, so a bond through paint or anodize is only a scratch. 100 mΩ, the protective-bonding figure of IEC 62368-1, is a pass mark every metal-to-metal joint clears by a factor of two or more, most by two orders, and every finished joint fails by five; the 0 V tie is held to 10 mΩ because a rail chafed onto the chassis returns its fault current through it.
EIS-GND-005	enclosure	An enclosure shall publish which of its metal parts, rails, inserts, sides, rear, and lid, are bonded to one another, and where its metalwork takes a bond to the row's 0 V.	inspection	In the common case the chassis is the inserts and the panels, and the anodized rails float; the installer who straps a case needs to know which parts are already one and where the strap lands.

6.4 The bus

ID	Applies to	Requirement	Verified by	Why
EIS-BUS-001	bus board, power supply (with a PWR-BUS outlet)	The bus shall provide +12 V and −12 V, and may provide +5 V, at every power header.	inspection	Every module may count on ±12 V at its header, while +5 V stays optional because many modules regulate their own.
EIS-BUS-002	module, bus board, cable, power supply (PWR-BUS)	A power header on a module or a bus board shall be a 2 × 5 or 2 × 8 pin header on a 2.54 mm grid, and a power cable shall end in IDC ribbon sockets that mate it, the socket at the bus-board end having as many positions as the header it mates.	inspection	Every Eurorack power ribbon and header in use has this form, so any conforming module and bus board connect without an adapter; a 10-position socket on a 16-pin bus header can be fitted one pin pair off and short +12 V to 0 V.
EIS-BUS-003	module, bus board, cable, power supply (PWR-BUS)	A power header on a module, a bus board, or a cable shall follow the pinout of clause 6.4: −12 V on pins 1–2, 0 V on 3–8, +12 V on 9–10, and on a 16-pin header +5 V on 11–12, CV on 13–14, and gate on 15–16.	inspection	Ribbons and bus boards made to a different pin order put +12 V on a module's 0 V pins; one pinout prevents that.
EIS-BUS-004	module, bus board, cable, power supply (PWR-BUS)	The marked conductor of a power ribbon cable shall be −12 V, and on a module, a bus board, or a power supply it shall lie at the −12 V end of the header.	inspection	A marked conductor tied to −12 V lets an installer orient a ribbon by eye at both ends, the only guide on an unshrouded header.
EIS-BUS-005	module, bus board, cable, power supply (PWR-BUS)	A shrouded power header on a module or a bus board shall be keyed so that, viewed from the mating side with the −12 V end at the bottom, the key gap is on the right, and a keyed cable socket shall match it.	inspection	A key in one fixed position lets a keyed socket enter a shrouded header only the right way round, whoever made each part.
EIS-BUS-006	module (with a PWR-BUS entry)	A module powered from the bus shall draw only +12 V and −12 V, and may also draw +5 V.	inspection	These are the only rails a conforming bus delivers, so a module that needs any other rail cannot run from a conforming row.
EIS-BUS-007	module (with a PWR-BUS entry)	A module that uses neither +5 V nor bus CV or gate may use the 10-pin header.	inspection	Pins 11 to 16 carry nothing such a module uses, so the smaller header saves board space without losing any connection.
EIS-BUS-008	module, power supply (with a PWR-BUS entry)	A module or a power supply shall not draw more than 1.5 A on any rail through one power header.	measurement: current on each rail through one header in operation, at most 1.5 A, the charging of its decoupling at power-up excluded	Each rail has two IDC contacts rated 1 A, and they share the current unevenly, up to about 2:1 through a short ribbon; 1.5 A keeps the busier contact at its rating.
EIS-BUS-009	module, power supply (with a PWR-BUS entry)	A module or a power supply shall tolerate reverse polarity at its power header without damage.	measurement: no damage after a ribbon reversed at the module end, and a 16-pin ribbon also reversed at the bus end, from a bench supply current-limited to the module's published currents	A reversed ribbon is the commonest field fault; surviving it keeps one mistake from destroying a module.
EIS-BUS-010	module (with a PWR-BUS entry)	A bus cable supplied with a module shall be keyed so that it enters a shrouded header only with the marked conductor on −12 V.	inspection	A keyed cable makes the shroud do its job, so the ribbon that ships with a module cannot be fitted backwards into a shrouded header.
EIS-BUS-011	module	A header on a module that is not its power header shall either not mate a Eurorack power ribbon socket or tolerate one fitted to it, either way round, without damage.	inspection	Expander and link headers often share the power header's form, and a power ribbon fitted to one puts ±12 V on its signal pins.
EIS-BUS-019	module, bus board, power supply (PWR-BUS)	A module, a bus board, and a power supply shall mark the −12 V end of each power header on the board.	inspection	The marked conductor of a ribbon can only be matched to the header when the board says which end is −12 V; on an unshrouded header the marking is the only guide.

6.5 Bus boards

ID	Applies to	Requirement	Verified by	Why
EIS-BUS-012	bus board, enclosure, power supply (with a PWR-BUS outlet)	The per-header limit a bus board, a built-in bus board of an enclosure, or a power supply publishes for its power-header outlets shall not exceed 1.5 A per rail.	inspection	A header carries each rail on two IDC contacts of about 1 A, the same limit modules are held to under BUS-008.
EIS-BUS-013	bus board (with a PWR-BUS outlet)	A bus board may split CV and gate into two regions.	inspection	A split lets one long bus board carry two separate CV and gate lines, each with its own transmitter.
EIS-BUS-014	bus board, cable (PWR-BUS)	A link between two bus boards shall join CV to CV and gate to gate.	inspection	A crossed link would send pitch CV to gate listeners and gate pulses to oscillators on the next board.
EIS-BUS-015	cable (PWR-BUS)	A power ribbon from a bus header to a module shall be no longer than 400 mm and shall use conductors of at least 28 AWG.	inspection	At the 1.5 A header limit a 400 mm, 28 AWG ribbon drops about 65 mV in a rail's two conductors and about 30 mV more in its contacts, under 1 % of 12 V; a longer or thinner ribbon eats further into the rails the module receives.
EIS-BUS-020	bus board	A bus board may also distribute a DC rail or the video sync behind the panel; it then meets the rules of what it carries: the PWR-DC12 outlet rules of 8.1, or the video sync ports of 8.2.	inspection	One board behind the panel can carry the bus, the DC rail, and the video sync tree; each outlet and port on it stays under the rule written for its interface.
EIS-BUS-021	bus board	A bus board may carry a 0 V strip: a band of its outer-layer 0 V plane left bare of solder mask along the board's length, with plated holes at its mounting-hole positions, on which a 0 V bus bar is clamped by screws through the bar and the holes; the strip's end holes take M4, and a ring terminal under an M4 screw of the strip or the bar is a 0 V terminal of the board.	inspection	A bar clamped on bare copper the length of the board puts every header's return and every link on one potential with no trace between them, and the strip's M4 holes, two rings on each, give a board in the middle of a chain the positions one stud cannot: its return and a link each way.
EIS-BUS-022	bus board (with a PWR-BUS outlet)	A bus board that splits CV and gate into regions shall mark on the board, and publish, which headers lie in each region.	inspection	ASM-002 allows one transmitter per line up to a region split; the installer can keep to it only if the split is visible and published.

6.6 Bus CV and gate

ID	Applies to	Requirement	Verified by	Why
EIS-BUS-016	module (with a PWR-BUS entry)	A module shall listen to or transmit bus CV or gate only when a jumper or switch on the module is set to do so.	inspection	The bus CV and gate lines are shared across a row, so a module left at its default never fights a transmitter or reacts to stray levels.
EIS-BUS-017	module (with a PWR-BUS entry)	A module that drives or receives bus CV shall meet the BUS-CV limits of clause 6.6.	measurement: BUS-CV scale at the header into 10 kΩ, within ±0.3 %; listener input impedance at least 100 kΩ	Every listening oscillator follows the one bus CV line, so shared levels and impedances keep any transmitter and listener in tune.
EIS-BUS-018	module (with a PWR-BUS entry)	A module that drives or receives bus gate shall meet the BUS-GATE limits of clause 6.6.	measurement: BUS-GATE high at least +4 V and low at most +0.5 V at the header into 4.7 kΩ; listener thresholds +3 V and +1 V	Shared thresholds and impedances let any module's gate on the bus register reliably at every listening module.

7.1 Signals

ID	Applies to	Requirement	Verified by	Why
EIS-SIG-001	module	A module shall publish a port list naming, for every port, its signal class or unclassified, and for a video sync port its mode (8.2).	inspection	The port list tells a user which class and limits each jack meets, so a patch can be checked before it is made.
EIS-SIG-002	module	A patch input shall withstand ±12 V indefinitely.	measurement: no damage after ±12 V from a source of 1 kΩ or less is held on each patch input	±12 V is the most a bus rail or any conforming output (SIG-004) can put on a jack, so an input that withstands it survives any patch.
EIS-SIG-003	module	A patch output shall withstand an indefinite short to 0 V or to another patch output.	measurement: no damage after each patch output is shorted to 0 V and to another output	Patching an output to 0 V or to another output is a routine mistake on a patch panel, and one cable must not destroy a module.
EIS-SIG-004	module	A patch output shall not drive the patch tip beyond ±12 V.	inspection	Keeping outputs within ±12 V keeps them within what every patch input is built to withstand under SIG-002.
EIS-SIG-015	module	A patch jack shall carry patched signals only: a module shall neither take nor give its video sync at a patch jack, and no patch jack shall list a format of clause 8.3.	inspection	The video sync is system cabling, not a patch: kept on the rear coaxial interface, it is never changed by patching, and no patch cable has to carry it.
EIS-SIG-018	module, bus board, enclosure	A product that generates or locks to an external video sync shall take or give it at a video sync port on its rear.	inspection	The video sync is system cabling: at the rear, on the coaxial interface, it is wired once behind the panel and stays out of the patch field.
EIS-SIG-017	module, bus board, enclosure, power supply	A jack inside the case shall not be a BNC jack: none at the rear of a module, on a bus board, or on a power supply. A BNC jack is on the outside of the case only, on a front panel or an enclosure's wall.	inspection	A BNC's bayonet sleeve needs room for fingers to grip and turn, which the space behind the panels and over a bus board lacks, and its height takes depth a ribbon or a module's board needs; an RCA jack mates with a push and an SMA with a few turns of a small nut. A facility video sync arrives at a BNC on the enclosure's wall and is wired inside to RCA or SMA.

7.2 Signal classes

ID	Applies to	Requirement	Verified by	Why
EIS-SIG-005	module	A port shall meet the limits of the class it names, at the range it names: an output keeps its full-scale signal within the range's ceiling, and an input accepts the range's full swing without clipping.	measurement: the class's level, impedance, and thresholds at the claimed range, from the class table of 7.2	One table of classes lets a patch between any two modules work at the levels both expect, and the range says which swing an output gives and an input takes.

7.3 Video signals

ID	Applies to	Requirement	Verified by	Why
EIS-SIG-009	module (VIDEO)	A VIDEO input shall present 100 kΩ ±1 % to 0 V at the patch tip.	measurement: 100 kΩ ±1 % to 0 V at each VIDEO input	A high, tightly held input impedance takes a 75 Ω output at almost unity gain, so video levels match from module to module. The figure is the resistance at the tip, resistor and stage together; a 1 % resistor costs what a 10 % one does.
EIS-SIG-010	module (VIDEO)	A VIDEO output shall drive the patch tip through a 75 Ω ±1 % series resistor.	measurement: 75 Ω ±1 % series resistor from the buffer output to the tip of each VIDEO output	A 75 Ω series source keeps a short unterminated patch cable from ringing, and one fixed value keeps level and edges alike from module to module.
EIS-SIG-019	module (VIDEO)	A VIDEO input that reads a signal as high or low, such as a comparator, logic, or key input, shall switch at a threshold of +0.5 V: it reads above the threshold as high and below it as low.	measurement: the input reads +0.45 V as low and +0.55 V as high	+0.5 V is the midpoint of the 0 to +1 V VIDEO scale, so any VIDEO output, a picture, a ramp, or another module's logic, drives any VIDEO logic input the same way, and a key or comparator splits a picture at mid-gray.
EIS-SIG-016	module (VIDEO)	A module shall publish, for each VIDEO output, the kind of path behind it and, for a linear or variable path, its −3 dB bandwidth measured as clause 7.3 states.	measurement: the −3 dB bandwidth of each linear or variable VIDEO path, relative to 100 kHz, from a 75 Ω source into 100 kΩ in parallel with 30 pF, by a method of Annex A	The kind says whether a bandwidth describes the path, and the figure, measured one way, says how sharp a picture it passes. EIS sets no minimum: a slow path is a design choice, and the figure says so.

Part 3 Optional interfaces

8.1 12 V DC power (PWR-DC12)

ID	Applies to	Requirement	Verified by	Why
EIS-DC-001	module, bus board, enclosure, power supply (with a PWR-DC12 entry)	A product shall publish its DC entry variant: DC-BAR21, DC-BAR25, DC-VH2, DC-DIN4, DC-MF6, or DC-MF8, as tabulated in 8.1.	inspection	The variant tells a buyer which plug, cable, and distribution product will physically mate with the product.
EIS-DC-002	module, bus board, enclosure, power supply (with a PWR-DC12 entry)	A product shall publish the minimum and maximum DC input voltage its DC entry accepts.	inspection	Nominal 12 V adapters vary in output, so the accepted range tells a buyer which adapters the product can safely use.
EIS-DC-003	module, bus board, enclosure, power supply (with a PWR-DC12 entry)	A DC entry shall not use the pinout of a Eurorack 10-pin or 16-pin power header.	inspection	A DC entry wired like a bus header invites a bus ribbon to be plugged into it, putting 12 V across the wrong pins.
EIS-DC-004	module, bus board, enclosure, power supply (with a PWR-DC12 entry)	A DC-BAR21 or DC-BAR25 barrel DC entry shall be center positive.	inspection	Center positive is the usual convention of 12 V adapters, so fixing it keeps a common adapter from reversing the DC rail.
EIS-DC-005	module, bus board, enclosure, power supply (with a PWR-DC12 entry)	A product with a DC-VH2, DC-DIN4, DC-MF6, or DC-MF8 DC entry shall implement the pin functions tabulated for that variant in 8.1.	inspection	Fixed pin functions let any cable or distribution product of that variant deliver +V and −V to the right pins.
EIS-DC-006	module, bus board, power supply, enclosure (with a PWR-DC12 entry)	A barrel DC entry, and every case DC entry, shall tolerate reverse polarity without damage.	measurement: no damage after a reversed input at the entry's rated voltage, from a source current-limited to its rated current	Center-negative adapters fit the same barrel, and a computer supply's 8-pin EPS12V cable is a Mini-Fit Jr 2 × 4 like DC-MF8 with its +12 V on the other row; a reversed plug must not damage the product.
EIS-DC-007	cable (PWR-DC12)	A straight DC barrel cable shall connect tip to tip and sleeve to sleeve at both ends.	inspection	A straight cable has to keep the center-positive polarity of both ends, or it reverses the DC rail it carries.
EIS-DC-008	cable (PWR-DC12)	A cable for a DC-VH2, DC-DIN4, DC-MF6, or DC-MF8 DC entry shall connect each pin to the same pin and function at both ends.	inspection	Pin-for-pin wiring keeps +V and −V where the far end expects them, so the cable never reverses or shorts the DC rail.
EIS-DC-009	module, bus board, power supply, enclosure (with a PWR-DC12 outlet)	A product with PWR-DC12 outlets to modules shall feed them only through DC-BAR21 jacks or DC-VH2 headers, and shall not use DC-BAR25 for an output to a module.	inspection	A DC-BAR25 plug enters a DC-BAR21 entry with unreliable contact, so outputs to modules use only connectors that fit module entries properly.
EIS-DC-010	cable (PWR-DC12)	A cable from a PWR-DC12 outlet to a module shall end in DC-BAR21 plugs or DC-VH2 housings and connect +V to +V and −V to −V, tip and pin 1 being +V.	inspection	Module entries are center positive with pin 1 at +V, so a distribution cable has to keep that polarity at both ends.
EIS-DC-011	module, bus board, enclosure, power supply (PWR-DC12)	A DC entry and each PWR-DC12 outlet shall be marked beside it with its polarity, a barrel by its polarity symbol and a multi-pin entry by its +V and −V pins, its nominal voltage, and its maximum current, and a DC entry also with the minimum and maximum input voltage it accepts.	inspection	An adapter is chosen at the entry and a cable at the outlet, so the marking beside the port is what keeps a wrong adapter or an overloaded outlet off a product.
EIS-DC-012	module, bus board, power supply, enclosure (with a PWR-DC12 outlet)	A product with PWR-DC12 outlets to modules shall protect each output separately and shall publish the current at which the protection acts.	inspection	One shorted cable on an unprotected output takes every module on the rail down; a limit per output keeps the fault to one module.
EIS-DC-013	module, bus board, power supply, enclosure (with a PWR-DC12 outlet)	A DC entry that feeds PWR-DC12 outlets shall tolerate reverse polarity without damage and shall not pass the reversed voltage to its outlets.	measurement: no damage after a reversed input, and no reversed voltage at any outlet	An entry that feeds a row is plugged by whoever assembles the case; a reversed adapter must not take the row with it.
EIS-DC-014	module, bus board, power supply, enclosure (with a PWR-DC12 entry)	A product with a case DC entry, a DC entry that takes an external adapter's output for a row: any DC entry of an enclosure, a power supply, or a bus board, or of a module with PWR-DC12 outlets or row wiring outputs, shall publish whether its 0 V is bonded to the chassis at the entry, and where.	inspection	The case DC entry is where a system fed from an adapter makes its one chassis tie; an installer who cannot tell whether the entry bonds 0 V to the chassis either leaves the case floating or ties it twice.

8.2 Video on 75 Ω coaxial jacks (VID-75)

ID	Applies to	Requirement	Verified by	Why
EIS-V75-001	module, bus board, enclosure (VID-75)	Every jack in a VID-75 tree shall be an RCA, BNC, or SMA jack.	inspection	The three jack types are electrically the same here, so any 75 Ω cable with the matching plugs joins any two products.
EIS-V75-002	module, bus board, enclosure (VID-75)	On every jack in a VID-75 tree, the center pin shall carry the video signal and the shell shall be 0 V.	inspection	One center and shell convention lets any coaxial cable carry the signal and join the 0 V of the products it connects.
EIS-V75-003	module, bus board, enclosure (VID-75)	A COAX-OUT or a buffered COAX-THRU shall drive one COAX-IN load, and an output shall not be split passively to several terminated ports.	inspection	A second termination on one output drops the level to two thirds and a third drops it to half.
EIS-V75-004	cable (VID-75)	A VID-75 cable shall be a 75 Ω coaxial cable, with RCA, BNC, or SMA plugs, that connects center pin to center pin and shell to shell at both ends.	measurement: cable impedance 75 Ω; center to center and shell to shell at both ends	A 75 Ω cable keeps the line impedance continuous from source to termination, so the tree stays matched and free of reflections.
EIS-V75-006	module, bus board, enclosure (with a COAX-IN)	A product with a video sync input shall take the video sync at a COAX-IN on its rear, lock any video timing of its own to it, and list the formats it accepts.	measurement: the module's video timing follows the video sync at its COAX-IN in each listed format	A COAX-IN says what a buyer needs to know first: this module follows the row's video sync, through this rear port, in these formats.
EIS-V75-007	module, bus board, enclosure (with a COAX-OUT)	A product with a video sync output shall generate video sync of a listed format itself and give it at a COAX-OUT on its rear; a copy of the video sync it takes at its COAX-IN is a COAX-THRU, not a COAX-OUT.	measurement: video sync of each listed format at the COAX-OUT, with nothing connected at the COAX-IN	An output means the module can be the row's video sync; a THRU cannot, and the two are easy to confuse on a panel marked OUT.
EIS-V75-008	module, bus board, enclosure (with a COAX-THRU)	A product shall have a video sync through only if it also has a video sync input, and each through shall be a COAX-THRU marked THRU. Its port list shall say which kind: buffered (a copy of the video sync at the COAX-IN, driven as a COAX-OUT into one COAX-IN load) or looped (a jack bridged to the COAX-IN jack on one line).	measurement: buffered: the video sync at the COAX-IN appears at the COAX-THRU at line level into 75 Ω; looped: the THRU jack is the COAX-IN line; the mark THRU beside the port	A THRU chains video sync through modules without a distribution product. Buffered, each THRU drives the next input; looped, one cable run passes every module with one termination at its end. The mark keeps either from being cabled as a source.
EIS-V75-009	module, bus board, enclosure (with a COAX-THRU)	A product with a looped COAX-THRU shall give its COAX-IN a termination switch, marked TERM, that presents 75 Ω to 0 V across the line when on and no load when off, and shall lock the same with the switch on or off.	measurement: 75 Ω to 0 V across the line with TERM on, no load with TERM off; the module locks either way	A looped line is terminated once, at its far end; the switch is what lets the last module on the run terminate it and every other module bridge it.
EIS-V75-010	module, bus board, enclosure (VID-75)	Every video sync port shall be a COAX-IN (75 Ω ±5 % to 0 V at the jack), a COAX-OUT (a 75 Ω ±5 % series source driven at twice the line level), or a COAX-THRU, buffered or looped, never a patch jack.	measurement: 75 Ω ±5 % to 0 V at each COAX-IN; twice the line level open-circuit, from 75 Ω ±5 %, at each COAX-OUT	The video sync tree works only when every port in it is terminated once and driven once; the port modes say what each jack does. A picture port on the front is listed in the port list by its Annex C class.
EIS-V75-011	module, bus board, enclosure (VID-75)	A video sync port shall be marked beside it as an input (IN), an output (OUT), or a through (THRU), and a termination switch shall be marked TERM.	inspection	The installer cables the video sync once, behind the panel, and reads the marking, not the manual.
EIS-V75-012	module, bus board, enclosure (VID-75)	A COAX-OUT port or a buffered COAX-THRU port shall pass the video sync with a −3 dB bandwidth of at least 30 MHz into a 75 Ω load.	measurement: −3 dB bandwidth of at least 30 MHz at each COAX-OUT and buffered COAX-THRU, into 75 Ω	A tri-level video sync edge is 54 ns ± 20 ns (SMPTE ST 274 and ST 296); a 30 MHz path keeps it inside that tolerance through a chain of buffered THRUs, and the buffers the trade uses for video sync distribution clear it with margin.

8.3 Video timing

ID	Applies to	Requirement	Verified by	Why
EIS-VID-001	module, bus board, enclosure (VID-75)	A product's port list shall name, for each video sync input (COAX-IN) and output (COAX-OUT), every format of clause 8.3 the port accepts or generates, by its format ID.	inspection	Listing formats by ID on the video sync ports lets a buyer check that a video sync generator and the modules that lock to it share a format; a patch jack lists none, because it is never the video sync.
EIS-VID-002	module, bus board, enclosure (VID-75)	For each format a port lists, the video timing a product generates at a COAX-OUT, and the video timing it locks to at a COAX-IN, shall match the format's publication within the tolerances that publication states; for a progressive format, and along the line for a high-definition interlaced format, the row of clause 8.3 is that publication's raster, sample for sample.	measurement: line and frame timing and the video sync structure of each listed format, within the publication's tolerances	Two products locked to one format have to agree on its raster. An analog interlaced format can be held only to its publication's tolerances, not to a clock-exact row; a sample-defined format is exact.

Part 4 Assembly

9 Assembling a system

ID	Applies to	Requirement	Verified by	Why
EIS-ASM-001	installer	A module shall be added to a row only while, on each rail of each power interface, the sum of the published currents stays within the published totals of every source and every product with outlets that feeds it, and the current through each outlet stays within that outlet's limit.	inspection	Exceeding a bus board, header, or supply rating overheats contacts or trips the supply; the published currents exist so it can be checked first.
EIS-ASM-002	installer	At most one module shall transmit on each CV line and at most one on each gate line, where a line runs across linked bus boards up to a region split.	inspection	Two transmitters on one line drive against each other, leaving a level that is neither and stressing both outputs.
EIS-ASM-003	installer	Installation shall connect only one of a product's alternative power entries at a time.	inspection	Two sources on one product can feed current from one into the other through its power circuit.
EIS-ASM-004	installer	Installation shall not insert a DC-BAR25 plug into a DC-BAR21 DC entry.	inspection	A DC-BAR25 plug enters a DC-BAR21 entry but makes unreliable contact, which can run hot or drop power under load.
EIS-ASM-005	installer	Each DC rail shall be fed from one adapter or one case DC entry at a time.	inspection	Two adapters or entries on one DC rail fight each other's regulation and can feed current back into each other.
EIS-ASM-006	installer	A DC-VH2, DC-DIN4, DC-MF6, or DC-MF8 DC entry shall be mated only with that variant's plug.	inspection	Each multi-pin variant has its own pin functions and contact rating, so only its own plug puts +V and −V on the right pins at its rated current.
EIS-ASM-007	installer	Each video sync tree in a row shall have exactly one source, a COAX-OUT or an external video sync at one COAX-IN, and each COAX-IN shall be fed by one output.	inspection	Two sources on one tree fight; an input fed by two outputs has two drivers on one line.
EIS-ASM-008	installer	Row wiring an installer adds between a power supply, bus boards, a DC entry, or PWR-DC12 outlets shall meet PWR-006 and PWR-007, with each ring terminal clamped on the product's M4 terminal under a lock washer, and a bond an installer adds shall meet PWR-008.	inspection	A supply and a bus board from different makers are joined by the installer; the wiring rules travel with the installer, not with either product.
EIS-ASM-009	installer	Where the bus boards of one enclosure are fed by more than one power supply, installation shall link their 0 V so that every bus board reaches, directly or through other boards' links, a bus board fed by each other supply, each 0 V link at most 2 mΩ terminal to terminal, and each bus board shall keep its own 0 V conductor to the supply that feeds it.	measurement: four-wire resistance of each 0 V link, terminal to terminal, at 20 to 25 °C	Two supplies joined only at their outputs put the drop of each one's conductors between two rows' references; a link between the bus boards holds every board's 0 V at one potential whatever each return carries. Hinton Instruments runs one common 0 V bar and links cases at under 2 mΩ for the same reason; between cases the 2 mΩ cannot be held past about 0.44 m on 10 AWG, so there EIS recommends the link instead.