Data String Contents
Byte Definition
Standard Enhanced  
1 1 A 1-character presentation space short name (PSID).
2–4 Reserved.
2 5 One of the following characters:
  • L to lock the API.
  • U to unlock the API.
3 6 One of the following characters:
  • R to return if the presentation space is already locked by an application.
  • Q to queue the Lock request if the presentation space is already locked by an application.
7–8 Reserved.