Throughout this document, diagrams illustrate XL Fortran syntax.
This section will help you to interpret and use those diagrams.
If a variable or user-specified name ends in _list, you can
provide a list of these terms separated by commas.
You must enter punctuation marks, parentheses, arithmetic operators, and
other special characters as part of the syntax.
- Read syntax diagrams from left to right and from top to bottom, following
the path of the line:
- The >>--- symbol indicates the beginning of a
statement.
- The ---> symbol indicates that the statement syntax
continues on the next line.
- The >--- symbol indicates that a statement continues
from the previous line.
- The --->< symbol indicates the end of a
statement.
- Program units, procedures, constructs, interface blocks and derived-type
definitions consist of several individual statements. For such items, a
box encloses the syntax representation, and individual syntax diagrams show
the required order for the equivalent Fortran statements.
- IBM and Fortran 95 extensions are marked by a number in the syntax diagram
with an explanatory note immediately following the diagram.
- Required items appear on the horizontal line (the main path):
>>-keyword--required_argument----------------------------------><
|
- Optional items appear below the main path:
>>-keyword--+-------------------+------------------------------><
'-optional_argument-'
|
- Note:
- Optional items (not in syntax diagrams) are enclosed by square brackets
([ and ]). For example, [UNIT=]u
- If you can choose from two or more items, they appear vertically, in a
stack.
If you must choose one of the items, one item of the stack
appears on the main path:
>>-keyword--+-required_argument-+------------------------------><
'-required_argument-'
|
If choosing one of the items is optional, the entire stack appears below
the main path:
>>-keyword--+-------------------+------------------------------><
+-optional_argument-+
'-optional_argument-'
|
- An arrow returning to the left above the main line (a repeat arrow)
indicates that you can repeat an item, and the separator character if it is
other than a blank:
.-,-------------------.
V |
>>-keyword----repeatable_argument-+----------------------------><
|
A repeat arrow above a stack indicates that you can make more than one
choice from the items in the stack.
.-,---------------------.
V |
>>-keyword----+-required_argument-+-+--------------------------><
'-required_argument-'
|
The following is an example of a syntax diagram with an
interpretation:
.-,-.
(1) V |
>>-EXAMPLE-------char_constant--+-a-+--+---+----e-+------------->
'-b-' +-c-+
'-d-'
>--name_list---------------------------------------------------><
Notes:
- IBM Extension
|
Interpret the diagram as follows:
- Enter the keyword EXAMPLE.
- EXAMPLE is an IBM extension.
- Enter a value for char_constant.
- Enter a value for a or b, but not for both.
- Optionally, enter a value for c or d.
- Enter at least one value for e. If you enter more than one
value, you must put a comma between each.
- Enter the value of at least one name for
name_list. If you enter more than one value, you must put a
comma between each. (The _list syntax is equivalent to the
previous syntax for e.)
