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CHAIN COMMAND
6.3 -- Compilation Operators
All
Compilation Operators
are included in
the
CHAIN rile
along with any other statements.
Compilation
Operators
are
denoted
~y
a
slash
e/)
appearing in the first column of a
"line.
An"y number of intervening spaces (including none)
can
be placed between the slash and the operator.
If an operator
is found which is not defined.
the
CHAIN
process
will
be
aborted.
The following Compilation Operators are defined:
Operator
'*
IFS
IFC
XIF
ELSE
ABORT
Function
Comment
Conditional "if set" test
Conditional "if clear" test
End conditional
Conditional alteTnative
Unconditional CHAIN abort
6.3.1 Compilation Comments
I'
the
character following a slash is an asterisk
<*),
then a Compilation Comment is indicated.
The
remainder
of
the
line
following the asterisk contains the comment,
which
can include any displayable characters.
Compilation Comments
are
not
urritten
into
the
int.ermediate
file.
They are,
however,
displayed on the console immediately after they
are
read 'rom the CHAIN file.
Compilation Comments are useful in
communicating to the operator what intermediate Tile is being
compiled for execution . . The comment lines are only displayed
if the part of the file
containing
the
comments
is
being
compiled into the intermediate file (see next section).
0.3.2 IF operator
If
the
characters
following
a
slash are IIIFu,
an IF
operator is denoted.
There may be any number
Or
intervening
spaces
between
the slash and the IF operator.
This feature
allows a structured type of CHAIN file to be constructed that
will
shoUJ
by
i.ts
physical
appearance
the
range
of the
conditional operators.
The IF operator allows a test
to "be
made
for
the
existence
of
one
01'
more tags on the CHAIN
command line.
If the test proves positive,
or true,
then the
lines
from
the CHAIN file following the IF operatoT will be
included in the intermediate file (written
to
the
CHAIN.SY
file>.
If,
however,
the test proves
negatiVE,
OT"
~alse,
then
the
subse~uent
lines will not be included
in
the intermediate
file.
The
lines
from
the
CHAIN file will be included or
excluded following the IF
operator
until
an
ELSE
or
XIF
operator (explained below) is encountered.
The IF operator has two forms:
IFS and IFC,
which stand
for "if set" and lIif clear
ll
,
respectively.
The IFS
operator
Page
06-05
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