If you have not yet sent the message, please listen to what JamesM is trying to tell you in posts 2 and 4, and do NOT say that. There is no way to sound polite while you are telling your boss that you made a decision about his calendar. Bosses do not like it when people who work for them tell them what to do.... I basically put couple of lines on top of the agenda to let him know that i "block out" his time.
Even with "subordinates", I don't think it would be wise in most situations to say "I am blocking your time". In a good working relationship, a boss respects his people, and often trusts them to organise their time. Even if he or she is calling a mandatory meeting, the meeting invitation would usually be polite: at the strongest, something like "I'm setting up a meeting at [....]. Please be sure to attend." Besides, if it's an Outlook meeting invitation, the time isn't normally blocked until the invitation is accepted.Yes I wont .. I understand the reason behind that. I would use this term for my sub-ordinates. [...]
There may be a regional (AE/BE?) difference here, James. While I agree that "block out" could be used, I've also frequently heard and used "block" in that context: "I'll block Monday afternoon for you", "Can you block a couple of hours for me?" Google searches for "block an hour" and "block some time" show examples of that usage (even after you weed out the irrelevant ones).[...] Please note that it's "block out", not just "block". "Block" is to hinder/deny/impede. "Block out" is to reserve time in this context.