Use GPEXST to insert an Execute Structure element into the open structure following the element pointer or to replace the element pointed at by the element pointer with an Execute Structure element depending on the current edit mode. If the specified structure does not exist, then the graPHIGS API creates a new empty structure.
This element is one of two different execute structure-type elements that can exist in a structure. The other execute structure-type element is the Conditional Execute Structure (GPCEXS) element.
Traversal of the structure in which the Execute Structure element exists causes invocation of the target structure as soon as the Execute Structure element is encountered. Although the graPHIGS API does not allow recursive structure networks, no error is generated by the creation of such a network. The graPHIGS API only generates an error when an attempt is made to execute the open structure. The behavior of the graPHIGS API when traversing a recursive structure network is undefined.