Writing for the real world

All MUNI buses here in San Francisco have these stickers on their rear doors. I like them because they teach an interesting lesson in writing. As there is no punctuation, those four lines of text in fact create 5 different messages, all of which are contextually relevant to passengers as they stand by those doors.

Doors open inward

Doors open inward for your safety

For your safety do not stand

For your safety do not stand in stepwell

Do not stand in stepwell

Similarly structured sentences can be found on signs in elevators informing you what to do, and not to do, in case of a fire.