Code Manual for CONTAIN 2.0 - Federation of American Scientists

A sub-block thus can begin with a leading keyword or variable and end with an EOI. It can begin
with a leading keyword or variable and end with the leading keyword or variable to the next subblock;
it can begin with an indentation without a leading keyword and end with an EOI. (The EOI ~
is the only keyword at the level of the sub-block in the latter case.) From the above definitions, it
follows that an EOI keyword, ifpresent, will always be written at the same level of indentation as
the sub-block that it terminates. This consistent positioning of the EOI should be quite helpful in
determining which sub-block is terminated by each EOI when multiple sub-block levels are present.
With the above definitions, it is now possible to give the ordering requirements for sub-blocks: (1)
A sub-block must be specified after the last keyword or leading variable that precedes it in the
template and is at a higher level than the sub-block. Similarly, the sub-block must be specified
before the next keyword or leading variable at a higher level. By induction, this rule constrains
quantities within a sub-block to be specified in the order given, with exceptions only as allowed by
the second rule. (2) However, within a contiguous group of sub-blocks at the same level, those subblocks
may be specified in any order. A contiguous group of sub-blocks is defined as one that is not
separated by a sub-block at a higher level. (It is not possible to have sub-blocks at a given level
separated by a sub-block at a lower level because the sub-block at the lower level is by definition
included in one of the higher level sub-blocks.) Since at the lowest level, individual non-EOI
keywords and leading variables each represent a sub-block, the second rule implies that within a
contiguous group of such items at the lowest level, those items can be specified in any order.
Two examples of the template format are given below. The first is:
***** ***** ***** ***** ***** ************************************************
KEY n (const)
[OPTION1] {OPTION2 or 0PTION3}
EOI
***** ***** ***** ***** ***** ************************************************
where “n”is defined as the number of values of “const” to follow the keyword KEY and OPTION 1,
0PTION2, and 0PTION3 are the three options associated with the KEY block. In this example,
KEY, “n,” “const,” and EOI are considered to be at the fust level in the input hierarchy, and
OPTION1, 0PTION2, and 0PTION3 are considered to be at the second level. The “n” and “const”
variables are required to immediately follow KEY in the input because of the ordering requirement
for variables following keywords. OPTION1 is truly optional, as indicated by its square brackets.
However, one of OPTION2 or OPTION3 must be selected, as indicated by the curly brackets. The
option keywords selected are required to follow KEY, the last keyword preceding them at a higher
level in the input hierarchy, and to precede EOI, the next keyword following them at a higher level.
However, they are not required to follow KEY immediately as are “n” and “const.” Since OPTION1,
0PTION2, and 0PTION3 are each considered sub-blocks at the lower level, they are not restricted
in the order in which they maybe specified with respect to each other. (However, the curly brackets
indicate that only one of 0PTION2 or 0PTION3 can be specified.) The EOI terminates the subblock
which begins at the same level of indentation as the EOI, in this case the sub-block beginning
with KEY and not with OPTION 1. In the input one might thus specify
Rev O 14-8 6/30/97