I cannot find a standard field holding the ‘Actual Revenue Labor’. Does it have a different name, or is it deliberately missing for some reason?

I can see these standard fields and the lack of Actual Revenue Labor is very obvious:

• Actual Cost
• Actual Cost Labor
• Actual Cost Non-Labor
• Budgeted Cost 
• Budget Cost Labor
• Budget Cost Non-Labor
• Expected Revenue
• Expected Revenue Labor
• Expected Revenue Non-Labor 
• Actual Revenue
•  
• Actual Revenue Non-Labor

If it is really missing, does anyone have the appropriate formula  for me to use to have a custom field to store this (would Actual Revenue - Actual Revenue Non-Labour work, or would it need to take into account other revenues (e.g. fixed price work items) and is it dependant on the billing type)? 

Thanks