The Postal Service Identification Number (PSIN) is the document’s identifier. Each PSIN includes a prefix that indicates what type of directive it is, as noted in the following table:
Prefix
Directive Type
HBK
Handbook
HC
Headquarters Circular
KIT
Kit
LAB
Label
MAN
Manual
MI
Management Instruction
MOP
Memorandum of Policy
NOT
Notice
POS
Poster
PS
Form
PUB
Publication
SGN
Sign
TAG
Tag
Following the prefix, the PSIN also includes a unique numerical code (e.g., PUB 223) or, for handbooks and management instructions, a unique alpha-numeric code (e.g., HBK AS-353 or MI AS-270-2000-5). The two-letter portion of the alpha-numeric code identifies the Postal Service policy manual or topic/organization to which the document relates, as noted in the table below:
Two-Letter Code
Manual or Topic/Organization
AS
Administrative Support Manual
DM
Domestic Mail Manual
EL
Employee and Labor Relations Manual
FM
Finance
IM
International Mail Manual
IS
Inspection Service Manual
PO
Postal Operations Manual
