[css-display] Which whitespace characters are allowed in run-in sequences? (original) (raw)

A run-in sequence is defined as

a maximal sequence of consecutive sibling run-in boxes and intervening white space and/or out-of-flow boxes.

There are various characters that may be considered white space or not depending on the context. I assume here it refers to what CSS Text calls document white space characters. I think a link to that definition would be useful.