49 CFR 1152.11 - Description of lines to accompany the system diagram map or information to be contained in the narrative.
Each carrier required to file a system diagram map or narrative shall list and describe, separately by category and within each category by state, all lines or portions of lines identified on its system diagram map or to be included in its narrative as falling within categories 1 thru 3 ( § 1152.10(b)(1) thru (3)) as follows:
(a) Carrier's designation for each line (for example, the Zanesville Secondary Track);
(c) County or counties in which each line is located;
(d) Mileposts delineating each line or portion of line; and
(e) Agency or terminal stations located on each line or portion of line with milepost designations.