Merge branch '303' into 'master'

YEP-303: has-limits

See merge request !40

yeps/yep-303.md

 ---
 yep: 303
 title: has-limits
-author: Blaise Thompson
-status: draft
+author: Blaise Thompson <blaise@untzag.com>
+status: accepted
 tags: trait
 post-history: 2020-04-22
+              2020-07-14
 ---
 
-This YEP is a stub.
+# Abstract
+
+This YEP defines the has-limits trait.
+
+This trait has been accepted.
+See built documentation at at [yaq.fyi](https://yaq.fyi/traits/has-limits).
+
+# Table of Contents
+
+[TOC]
+
+# Motivation
+
+A subset of positional hardware has exactly two limits.
+This trait standardies the interface to such hardware.
+
+This trait requires has-position, see [YEP-301](https://yeps.yaq.fyi/301/).
+
+# Proposal
+
+## config: limits
+
+type: array
+
+default: [-inf, inf]
+
+Configuration limits are strictly optional.
+
+## config: out_of_limits
+
+type: enum
+
+default: closest
+
+Control behavior of daemon when set_position is given a value outside of limits.
+
+## state: hw_limits
+
+type: array
+
+## message: get_limits
+
+response: {'type': 'array', 'items': 'float'}
+
+Get daemon limits.Limits will be the intersection of config limits and driver limits (when appliciable).
+
+## messages: in_limits
+
+parameters: position: float
+
+response: boolean
+
+Check if a given position is within daemon limits.
+
+# Discussion
+
+Discussion can be found on the [gitlab issue](https://gitlab.com/yaq/yeps/-/issues/16) for this YEP.
+
+# Copyright
+
+This document is placed in the public domain or under the CC0-1.0-Universal license, whichever is more permissive.