EXTRN instruction

The EXTRN instruction identifies "external" symbols referred to in this source module but defined in another source module. These symbols are external symbols.

Read syntax diagramSkip visual syntax diagram>>-+-----------------+--EXTRN----------------------------------->
   '-sequence_symbol-'         
 
   .-,-------------------------------.  
   V                                 |  
>----+-external_symbol-------------+-+-------------------------><
     |       .-,---------------.   |    
     |       V                 |   |    
     '-PART(---external_symbol-+-)-'    
 
sequence_symbol
is a sequence symbol.
external_symbol
is a relocatable symbol that:
PART(external_symbol)
external_symbol is a relocatable symbol as described above, that also:

Up to 65535 individual control sections, external symbols, and external dummy sections can be defined in a source module. However, the practical maximum number depends on the amount of table storage available during link-editing.

The assembler lists each external symbol identified in a source module in the external symbol dictionary, along with entries for entry symbols, common control sections, parts, and external control sections.

A symbol identified by an EXTRN instruction should not also be declared by an ENTRY instruction.

External symbols have a length attribute of 1. See also WXTRN instruction.


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