The pseudo-attribute processing instruction (PI) indicates that a pseudo-attribute has a value for a given tag. This type of PI is visible only in the SGML source.

For example, the processing instruction

indicates that the preceding element has the _id pseudo-attribute set to f1.

You can delete pseudo-attribute PIs using the write -nopi command. You can also manipulate them using ACL functions such as oid_delete_attr and oid_modify_attr. Find > Processing Instruction does not locate pseudo-attribute processing instructions.