Administration > Environment Variables > APTEXPORTEXT — Providing an Alternative File Extension for Exported Files
  
APTEXPORTEXT — Providing an Alternative File Extension for Exported Files
To override the default .exp file name extension for files exported from Arbortext Editor by usetext constructs with userule =1. Include the “.” as part of the custom extension.
By default, the base names of these files are constructed by using the name of the element or pseudo-element whose e-i-c contains the usetext. Modify this behavior by using a userule hook.