Subpages are a powerful means of factoring out commonly used page functionality in your application. Rather than duplicating the same set of page fields on two or more pages, you can create a single subpage that contains those page fields and add it to any page. This makes it much easier to maintain the functionality that these page fields represent.

Subpages are even more effective when used with corresponding subrecords. In order to support the use of subrecords with subpages, the system uses a record name substitution mechanism for subpage-type page fields. Each subpage has a "from" record, determined dynamically by the page definition in PeopleSoft Application Designer and by the PeopleSoft Pure Internet Architecture. The "from" record is a record associated with one of the page fields in the subpage. Which page field depends upon the page field ordering, the types of page fields on the subpage, and whether it's record is a subrecord. The subpage itself must be fully expanded in order to make this determination. (This is important to keep in mind when working with subpages that contain other subpages.)

The "to" record is specified by you in the SubPage Record Name Substitution group box in the Insert Subpage dialog box that displays after you insert the subpage into a page (and on the Subpage tab of the Subpage Properties dialog). At runtime, when a subpage-type page field is expanded, each page field that is associated with the dynamically determined "from" record is instead associated with the "to" record you specify. This means, for example, that a subpage can be populated with page fields that are associated with a subrecord so that the subrecord is determined to be the "from" record. Then when that subpage is used as a subpage-type page field, you can specify the "to" record as one of the records that contains that subrecord. This enables you to associate a single set of page fields (through the subpage) with a variety of different records (each containing the subrecord).