# Max interfaces in the specification

**URL:** <https://forum.opencyphal.org/t/max-interfaces-in-the-specification/437>\
**Category:** Development & Maintenance\
**Created:** [April 11, 2019, 3:20am UTC](https://forum.opencyphal.org/t/max-interfaces-in-the-specification/437 "2019-04-11T03:20:54Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![scottdixon](https://forum.opencyphal.org/user_avatar/forum.opencyphal.org/scottdixon/32/39_2.png) [@scottdixon](https://forum.opencyphal.org/u/scottdixon)\
**Post date:** [April 11, 2019, 3:20am UTC](https://forum.opencyphal.org/t/max-interfaces-in-the-specification/437/1 "2019-04-11T03:20:54Z")

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I came across this in libuavcan:

```auto
/**
 * This limit is defined by the specification.
 */
enum { MaxCanIfaces = 3 };

```

Which I’ve seen before but I’ve forgotten what in the v0 specification governed this. Does anybody remember? @pavel.kirienko?

---

<div class="post-metadata">

**Author:** ![pavel.kirienko](https://forum.opencyphal.org/user_avatar/forum.opencyphal.org/pavel.kirienko/32/9_2.png) [@pavel.kirienko](https://forum.opencyphal.org/u/pavel.kirienko)\
**Post date:** [April 11, 2019, 1:57pm UTC](https://forum.opencyphal.org/t/max-interfaces-in-the-specification/437/2 "2019-04-11T13:57:42Z")

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The only place where the limit is used in the entire specification (assuming that the standard DSDL defs are part of it) is this:

> <https://github.com/UAVCAN/dsdl/blob/3baa2e90a0e8c7b660a2deda8f9a541877ed58e5/uavcan/node/434.GetTransportStatistics.0.1.uavcan#L19>