Conditional processing attribute values with groups

For more advanced needs, groups can be used to organize metadata into subcategories within a conditional processing attribute.

Grouped values are intended to support situations where a metadata attribute applies to multiple specialized subcategories. For example, if content is classified into two distinct types of product, those distinct types can become named groups within the @product attribute. The grouping syntax exactly matches the syntax used for generalized attributes, making it valid inside @props and any attribute specialized from @props, including those integrated by default in the OASIS-provided document-type shells: @audience, @deliveryTarget, @platform, @product, @otherprops.

The following rules apply to groups within conditional processing attributes:

• Groups consist of a name immediately followed by a parenthetical group of zero or more space-delimited string values. For example, "groupName(valueOne valueTwo)".
• Groups cannot be nested.
• If two groups with the same name are found in a single attribute, they are treated as if all values are specified in the same group. The following values for the @otherprops attribute are equivalent:

  otherprops="groupA(a b) groupA(c) groupZ(APPNAME)"
  otherprops="groupA(a b c) groupZ(APPNAME)"

• If both grouped values and ungrouped values are found in a single attribute, the ungrouped values belong to an implicit group; the name of that group matches the name of the attribute. Therefore, the following values for the @product attribute are equivalent:

  product="a database(dbA dbB) b appserver(mySERVER) c"
  product="product(a b c) database(dbA dbB) appserver(mySERVER)"

An empty group within an attribute is equivalent to omitting that group from the attribute. For example, <ph product="database() A"> is equivalent to <ph product="A">. Similarly, <ph product="operatingSystem()"> is equivalent to <ph product="">, which in turn is equivalent to <ph>.

If two groups with the same name exist on different attributes, a rule specified for that group will evaluate the same way on each attribute. For example, if the group "sample" is specified within both @platform and @otherprops, a DITAVAL rule for sample="value" will evaluate the same in each attribute. If there is a need to distinguish between similarly named groups on different attributes, the best practice is to use more specific group names such as platformGroupname and productGroupname. Alternatively, DITAVAL rules can be specified based on the attribute name rather than the group name.

If the same group name is used in different attributes, a complex scenario could be created where different defaults are specified for different attributes, with no rule set for a group or individual value. In this case a value might end up evaluating differently in the different attributes. For example, a DITAVAL can set a default of "exclude" for @platform and a default of "flag" for @product. If no rules are specified for group oddgroup(), or for the value oddgroup="edgecase", the attribute platform="oddgroup(edgecase)" will evaluate to "exclude" while product="oddgroup(edgecase)" will resolve to "flag". See DITAVAL elements for information on how to change default behaviors in DITAVAL profile.