Relocatable Object Module Format (OMF) Specification

Relocatable Object Module Format
C8H or C9H NBKPAT—Named Backpatch Record
Description
The Named Backpatch record is similar to a BAKPAT record, except that it refers to a COMDAT record by logical
name index rather than an LIDATA or LEDATA record. NBKPAT records must immediately follow the
COMDAT/FIXUPP block to which they refer.
History
This record is an extension to the original set of 8086 object record types. It was added for Microsoft C 7.0.
Record Format
1 2 1
C8 Record Location
or C9 Length Type
1 or 2 [1]
[2] 2 or 4 2 or 4 1
Public Offset Value Checksum
Name
Location Type Field
Type of location to be patched; the only valid values are:
0 8-bit byte
1 16-bit word
2 32-bit double word, record type C9H only
Public Name Field
[1] Microsoft LINK recognizes this field as a regular logical name index of the COMDAT record to be back patched.
[2] IBM LINK386 recognizes this field as a length-preceded name of the COMDAT record to be back patched.
Offset and Value Fields
These fields are 32 bits for record type C8H, 16 bits for C9H.
The Offset field specifies the location to be patched, as an offset into the COMDAT.
The associated Value field is added to the location being patched (unsigned addition, ignoring overflow). The
Value field is a fixed length (16 bits or 32 bits, depending on the record type) to make object module processing
easier.
Tool Interface Standards (TIS) OMF Specification, Version 1.1 67