49 C.F.R. § 1242.05 – Operating expense account number notation.

(a) The operating expense account numbers consist of a six-digit coding structure divided into three two-digit groups. The first two-digit group denotes natural expenses; the second group denotes activities/subactivities for freight, passenger or common service; and the third group signifies applicable function assignment.
(b) For reporting purposes, four natural expense categories are utilized. The categories are: salaries and wages (account 11-XX-XX); material, tools, supplies, fuels and lubricants (account 21-XX-XX); purchased services (accounts 31-XX-XX to 41-XX-XX, inclusive); and general (accounts 61-XX-XX to 65-XX-XX, inclusive, 51-XX-XX, 52-XX-XX, 53-XX-XX and 12-XX-XX).
(c) The symbol “XX” in the first two-digit group is used throughout the separation instructions to denote more than one natural expense associated with the same activity/subactivity-function account structure. For reporting purposes, the natural expense account numbers represented by “XX” include:
11—Salaries and wages; 21—Materials, tools, supplies, fuels, and lubricants; 30 or 41—Purchased services: 30—Summation of certain purchased service accounts; 41—Other purchased services; 61—General.
(d) The “30” natural expense designation indicates a summation of specific purchased service accounts that are reported in total rather than individually. The specific accounts under the way and structures activity except for administration functions include 39-1X-XX, repairs billed by others, Dr.; 40-1X-XX, repairs billed to others, cr.; and 41-1X-XX, other purchased services. For the equipment activity excluding administration functions, the “30” designation denotes the summation of 39-2X-XX and 41-2X-XX.
(e) The “41” natural expense designation (other purchased services) is the purchased service category of the “XX” code for the following:
1. (1) Way and structures activity administration—function accounts,
2. (2) Equipment activity administration—function accounts,
3. (3) Transportation activity expense accounts, and
4. (4) General and administration activity expense accounts.
(f) The “61” general natural expense designation is applicable to all accounts with the “XX” symbol except transportation, train and yards accounts (XX-(33/43/53)-XX).
(g) The natural expense account number “50” is used throughout the separation instructions to indicate the summation of accounts 52-XX-XX, Other casualties, and 53-XX-XX, Insurance, that are reported as one item, “Casualties and Insurance,” (50-XX-XX).
(h) The number “98” in the function account group (last two digits) is used in the separation rules to designate the summation of a natural expense consisting of more than one functional assignment that is reported as one item. This includes Repairs Billed to Others, Cr.—Equipment (40-2X-XX). For example, the locomotive subactivity contains accounts 40-(21/24/26)-40, 40-(21/24/26)-41, and 40-(21/24/26)-48 which are treated as 40-(21/24/26)-98.