Force preservation of left/right page orientation

[paul.n]

If a republisher deletes one half of a spread, we know that this throws off the l/r orientation of all subsequent pages in formats like Book Reader. This is bad.

However, if a republisher, deletes, say, the right page of spread1, and the left page of spread2 -- that preserves the orientation of subsequent pages (this method is sometimes employed when working with very tight margins or a centerfold). This is OK.

Currently, we are not blocking users from checking in books where the left/right gets thrown off.

I provided two examples because we do not want to enforce a rule that says only full spreads (l and r images) must be deleted.

Instead, we want to ensure that: if just one-half of a spread is deleted, then one-half of the opposite side of the next spread must also be deleted. Visual example below.

BAD, must be blocked from upload
[ ][x], [ ][ ]

OK, can be uploaded
[ ][x],[x][ ]

[danh (danh-archive)]

tracked elsewhere.