Coding Considerations › Keywords and User-supplied Names

Keywords and User-supplied Names

Keywords

Keywords are predefined names or special characters that are either required (shown as uppercase in syntax diagrams) or optional (shown as lowercase). You can enter the full keyword or abbreviate each keyword to a minimum of three characters, provided that no other keyword in the same syntactical position is abbreviated identically. The keywords ELEMENT and VERSION are exceptions to the three-character minimum; they can be abbreviated to EL and V, respectively. Keyword abbreviations that require more than three characters are noted in the syntax.

User-supplied Names

User-supplied names are names that you define. In addition to the character set restrictions, observe these points when you define names:

• Names must be unique.
• Names must not duplicate any of the reserved words of a specific compiler or assembler, and they must observe the compiler's character set and word-length restrictions.
• Names must be 1 to 32 characters (with noted exceptions).
• Valid characters for names:
  • Letters (A through Z) (uppercase or lowercase)
  • Digits (0 through 9)
  • At sign (@)
  • Dollar sign ($)
  • Pound sign (#)
  • Hyphen (-) (the first and last character in a name can't be a hyphen)
  • Underscore (_)
• A name must include at least one nonnumeric character.
• When you assign names to user-defined nests, comment keys, and alternative picture keywords, the DDDL compiler classifies each word and places it in the first appropriate category, as follows:
  1. DDDL keyword
  2. User-defined comment key
  3. User-defined nest
  4. User-defined nest inverse key
  5. Alternative picture keyword (ELEMENT entity type only)
  6. Class name

  For example, if a user-defined comment key that is not enclosed in quotation marks is the same as a DDDL keyword, the DDDL compiler interprets the comment key as a DDDL keyword.