This is a Federal Railroad Administration notice of availability and request for public comment on a joint request for amendment (RFA) submitted July 25, 2025, by 21 host railroads to their FRA-approved Positive Train Control Safety Plans (PTCSPs). The RFA covers an update to onboard software Version 6.5.5.0 for Interoperable Electronic Train Management Systems, which requires modifications to the ITC PTC Concept of Operations and the human-machine interface. FRA may approve, approve with conditions, or deny the RFA. This is a procedural regulatory notice, not a NEPA environmental review; no environmental impacts or mitigations are analyzed.12