4.1. Guidelines for Simple Named Expressions

Procedure

  1. The syntax to surround a named expression is $ExpressionName$.

    Example

    Expression Saved as Insertion Syntax
    Order Card OC $OC$
    Note: The $name$ syntax works just like an #include directive in the “C” programming language. The $name$ is removed; the text it represents is inserted; the expression evaluation continues.
  2. A partial identifier or a partial literal will not work as a named expression.

    Example

    Assume

    Order Card is an attribute group.

    The following expression is invalid:

    Given

    O = Order
    C = Card

    This will not work because the group name is split in half.

    $O$ $C$.A=’xyz’ fails.

    A single token in the bnf syntax in the detail design is the smallest an expression can be.

    Fractional tokens as demonstrated in this example are not supported.

  3. No substitution occurs between quotes.

    The following expression is invalid:

    Given:

    val= xyz

    Order Card.A=’$val$’ fails.

    The following expression is valid.

    Given:

    “val=’xyz’”

    “Order Card.A=$val$“ succeeds.

  4. Expressions are context sensitive.