49 C.F.R. § 229.315 – Operations and maintenance manual.

(a) The railroad shall maintain all documents pertaining to the installation, maintenance, repair, modification, inspection, and testing of a product subject to this part in one Operations and Maintenance Manual (OMM).
1. (1) The OMM shall be legible and shall be readily available to persons who conduct the installation, maintenance, repair, modification, inspection, and testing, and for inspection by FRA.
2. (2) At a minimum, the OMM shall contain all product vendor operation and maintenance guidance.
(b) The OMM shall contain the plans and detailed information necessary for the proper maintenance, repair, inspection, and testing of products subject to this subpart. The plans shall identify all software versions, revisions, and revision dates.
(c) Hardware, software, and firmware revisions shall be documented in the OMM according to the railroad's configuration management control plan.
(d) Safety-critical components, including spare products, shall be positively identified, handled, replaced, and repaired in accordance with the procedures specified in the railroad's configuration management control plan.
(e) A railroad shall determine that the requirements of this section have been met prior to placing a product subject to this subpart in use on their property.