If you were to determine:

• What week I am in
• The epoch start and epoch end value of the week
• The epoch start and epoch end of each blackout period within the current week

perhaps place the epoch start ends in a HOL, then iterate through checking your that your current time is not between any of the start/end times in the hash.

If I understand it right, you only want to check your current time against those in you xml file that have start and end times. The idea here is to collect all of them in one place in epoch format, check against each pair, and if now is not between any of them, do some action.

But then I may be way off track here too.. .

Thanks for posting the problem. It is related to some things I do every day with event based data, and it is good to try to see into a similar problem from a different perspective..