Rules for DDS keywords and parameter values

When you code data description specifications (DDS) entries, you must follow these conventions for entering keywords and their parameters.

The DDS coding syntax for keywords and their parameter values is similar to the CL syntax. The DDS syntax rules are:

  • Code all DDS entries in uppercase except for character values enclosed in single quotation marks and extended names enclosed in quotation marks.
  • Code keywords on the same (or subsequent) line as the entry with which they are associated.
  • Separate multiple keywords with at least one blank. Parameter values for keywords must be enclosed in parentheses. The initial parenthesis must immediately follow the keyword. For example: 
    KEYWORD(VALUE)

    This rule is slightly different from that in control language. When coding control language, the parameter values can be positional. Syntax for DDS requires that the keyword be specified, except when specifying either a constant or the parameter value for the DFT (Default) keyword.

  • Separate multiple parameter values for the same keyword with at least one blank. For example: 
    KEYWORD(VALUEA VALUEB)
  • A parameter expression consists of a set of values surrounded by left and right parentheses. Generally, the first value within the expression is a special value. The special value begins with an asterisk and must immediately follow the left parenthesis. One or more parameter values follow the special value. Separate the special value and the parameter value(s) by at least one blank. The last parameter value must immediately precede the right parenthesis. A parameter expression represents one parameter value and must be separated from other parameter values by at least one blank. For example: 
    KEYWORD(VALUEA (*special-value VALUEB) VALUEC)
  • Use single quotation marks to enclose character values. Numeric values appear without single quotation marks. See the coding examples for COMP, RANGE, and VALUES keywords. Character values can appear in two places in the syntax:
    • As a parameter value for some keywords. For example, TEXT (all types of files) and COLHDG (database files) require character strings as text description. Other keywords, such as CAnn and CFnn, use character strings as text descriptions for response indicators.
    • As the default value of a constant field (either with or without the DFT keyword) for display and printer files only. In display files, a character constant can also be specified for named fields. Even if you do not specify the DFT keyword, specifying a character constant implies the DFT keyword.
  • To specify a single quotation mark within a character string, specify two single quotation marks so that one single quotation mark appears in the output. For example: 
    KEYWORD('Customer''s name')
    appears as 
    Customer's name
  • Use a plus (+) or a minus (–) sign as a continuation character when a keyword and its parameter values do not fit on a single line. The sign must be the last nonblank character in the functions field. A single statement can be continued for a maximum of 5000 character positions.
    • A minus (–) sign means that the continuation begins in position 45 of the next line (the first position in the functions field).
    • A plus (+) sign means that the continuation begins with the first nonblank (first significant) character in the functions field on the next line.

    If you specify a continuation character within a parameter value, any blanks preceding the continuation character are included in the parameter value.

  • Specify a plus (+) sign as the last nonblank character on a line to continue conditioning for keywords specified on the next line. This is helpful when a condition includes several option indicators and applies to several keywords.
  • The operating system continues a DDS statement until you specify one of the following fields:
    • A record format name (R in position 17).
    • A field specification (field name or location).
    • For physical or logical files, a key field specification (K in position 17).
    • For logical files, a select or omit specification (S or O in position 17).
    • For join logical files, a join specification (J in position 17).
    • For display files, a help specification (H in position 17).
    • For device files, an option indicator or condition name that conditions a keyword, field, or field location.
    • The maximum length of a DDS statement (5000 characters). The fixed length entries (positions 1 through 44) of the first line are included in the statement, so the maximum space available for keywords is 4956.