Date   : Mon, 31 Dec 1984 22:39:00 GMT
From   : mpackard%uok.uucp@BRL-TGR.ARPA
Subject: Re: .REL Format

[]

This is the format for .REL files:

These files are bit-streams rather than byte-streams.

| 1 | XX | XXXX | XX XXXXXXXXXXXXXXXX | XXX+CHARACTERS OF SYMBOL NAME|
  ^   ^     ^            ^                        ^
  |   |     |            |                        |
Always 1    |            |                        |
      |     |          A Field                  B Field
      |     |                             Chars are 8 Bit ASCII
     00 - special link (see below)
     01 - program relative
     10 - data relative
     11 - common relative
            |
            |
Control Field:

The following special link items have a B field only

 0 - Entry Symbol (name for search)
 1 - Select COMMON block
 2 - Program name
 3 - Request library search
 4 - Reserved

The following special link items have both an A field and B field

 5 - Define COMMON size
 6 - Chain  external (A is head of address chain,  B is name  of 
     external
 7 - Define entry point (A is address B is name)
 8 - External offset. Used for JMP and CALL to externals

The following special link items have an A field only

 9 - External  + offset.  The A value will be added to  the  two 
     bytes  starting at the current location counter  immediately 
     before execution.
10 - Define the size of the Data area. (A is the size)
11 - Set the loading location counter to A
12 - Chain address.  A is the head of chain,  replace all entries 
     in  chain with current location counter.  The last entry  in 
     the chain has an address field of absolute zero.
13 - Define program size
14 - End of program (forces to byte boundary)

The following special link item has neither an A nor a B field

15 - End File