Relocatable Object Module Format (OMF) Specification

Relocatable Object Module Format
C4H or C5H LINSYM—Symbol Line Numbers Record
Description
This record will be used to output line numbers for functions specified through COMDAT records. Each LINSYM
record is associated with a preceding COMDAT record.
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
1 or 2 [1]
[2] 2 2 or 4 1
C4 Record Flags Public Line Line Checksum
or Length Name Number Number
C5
Offset
Flags Field
This field contains one defined bit:
01H
Continuation bit. If clear, this COMDAT record establishes a new instance of the COMDAT variable;
otherwise, the data is a continuation of the previous COMDAT of the symbol.
Public Name Field
[1] Microsoft LINK recognizes this field as a regular logical name index indicating the name of the base of the
LINSYM record.
[2] IBM LINK386 recognizes this field as a length-preceded name indicating the name of the base of the LINSYM
record.
Line Number Field
An unsigned number in the range 0 to 65,535.
Line Number Offset Field
The offset relative to the base specified by the symbol name base. The size of this field depends on the record
type.
Notes
Record type C5H is identical to C4H except that the Line Number Offset field is 4 bytes instead of 2.
This record is used to output line numbers for functions specified through COMDAT records. Often,
the residing segment as well as the relative offsets of such functions is unknown at compile time, in
that the linker is the final arbiter of such information. For such cases, most compilers will generate this
record to specify the line number/offset pairs relative to a symbolic name.
64 OMF Specification, Version 1.1 Tool Interface Standards (TIS)