Tandy 1000 MS-DOS Reference Manual page 269

Common
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Chapter 12 / Link Technical Reference
Common segments of the same
name and class name are loaded
overlapping one another. There
is only one canonical frame for
all common segments of the same
name. The length of the common
area is the length of the longest
segment.
Placing segments in a group in the assembler provides offset
addressing of items from a single canonical frame for all seg-
ments in that group.
Segments are partitioned by declared class names. The linker
loads the segments belonging to the first class name encoun-
tered, then loads all the segments of the next class name encoun-
tered, and so on until all classes are loaded.
If your program contains:
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DS:DGROUP
Any number of other
segments can intervene
between segments of a
group.
Thus, the offset of ZOO
can be greater than
the size of segments in
the group combined,
but no larger than
64K.
A
B
C
D
E
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zool
SEGMENT
SEGMENT
SEGMENT
SEGMENT
SEGMENT
0 - relative offset
An operand of
DGROUP ZOO in
assembly language
returns the offset of
ZOO from the
beginning of the first
segment
(Segment A here).
'ZOO'
'BAZ'
'BAZ'
'NEW'
'ZOO'
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