Ginnine Robar Dec 14, 2015:

Possible synonyms I agree that "work order" is an appropriate translation. However I see that "commander" also appears a couple of times in that paragraph, which means you are probably hoping to avoid to much repetition of the word "order."

Assignments or tasking (as a noun) are possibilities.

In the IT world, we talk about "tickets" which are essentially work orders for IT technicians. For example, a new employee is hired so a ticket is generated for creating a profile for that employee (username, passwords, email accounts etc.), or you can have support tickets for resolving technical problems. I can't quite tell from your paragraph what department is dealing with the ordre de mission, but if it relates to the IT technicians at all then ticket gets my vote.