In a response to a question in an India forum somebody answered that all items you leave in the Mumbai CTS cloak room must be "locked":
The cloak room charges something like Rs15 per item, and all items must be locked, you'll need your train ticket and passport
We have a couple of backpacks, what does it mean "locked" when applied to a backpack?
Locked means there is a lock on it. For a backpack, if you lock the main compartment and perhaps the secondary one, it should effectively be considered locked. This of course does little to ensure contents of the pack remain in the pack but if you have to do it according to some rules, it should do.
To lock it more effectively, place it in a wire metal mesh and lock that. The ones I use are from Pacsafe also allow attachment to a fixture which makes getting away with the bag harder. In some places you can easily find something suitable but not always.
