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CHAIN COMMAND
6.3 -- Compilation
Ope~ators
P
l'
ov
e
s p
0
sit
i
ve iTa
n
y
0
T
the ta 9 s 1 i s ted as its
0
per
and h a v e
-, - ,
-J
been specified on
the
CHAIN command line.
For example,
IIFS LIST
will prove positive
if
the tag
LIST
was
mentioned
on
the
CHAIN
command
line.
The
same test
~ill
prove negative if
LIST did not a p pea
1" •
L
i
k stu
i
s e;
the IF
0
per
a
tor
lIFe DAY
will prove positive ir the
tag
DAY was not speciried
on
the
CHAIN
command
line.
The
test
~ill
prove negative
if
DAY did
appea~.
Multiple IF operators
can
appeal'
in sequence
to
see
ir all tags of a certain group
~ere
speciFied.
Thus,
IIFS FLAG!
IIFS FLAG2
IIFS FLAG3
will prove positive only
if
tags FLAG 1
I
FLAG21
and
FLAG3
~ere
specified on the CHAIN command line.
More than one tag can appear in the operand field of
an
IF operator.
A comma separating
tag names
on an
IF
line will
perform an
"i~clusive
or" function.
A period separating
tag
namesl
on
the
other
handl
wi
11 perform an "and"
-function.
The "and
l l
function has precedence
ovel'
the
"or"
-function.
.,/'i
Th
at
is,
the
comma s ( or ) can bet
h
0
ugh t
0
f
as 9 r
0
up i n g
the
perio~s
(and).
For
examplel
the IF operator line
IIFS FLAG1.FLAG2.FLAG3
is equivalent to the previous example
o~
three successive
IF
operators.
The
~ollob.ling
linel
IIFS Fl. F2,FLAG3,TAG1.TAG2. LIST
~hich
can
be thought of as being evaluated
b~
the
~ollowing
grouping)
(Fl
and
F2) or (FLAG3) or (TAG1 and TAG2 and LIST)
will prove positive
ir
the
tags
Fl and F2 are
speci~ied,
or
if
FLAG3 is specifiedJ
01"
if
tags TAGl and TAG2 and LIST are
specified.
If
one
IF
subsequent
lines
operators, will be
or
XIF
operatol'
used to modify the
operator
has
proven
negativel
then
the
~ l'
om
the
C HA I N
f i
1
e l i
n c 1 u din got h e
T'
IF
ignol'ed until either a corresponding
ELSE
is
~ound.
In ·this way,
the
IF operator is·
resultant intermediate File.
Page
06-06
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