207: Unmatched right cross or unmatched right fork

The left cross +- is used together with the right cross -+ to cross out text. The left fork =- is used together with a right fork -= to mark inline notes. You used one of the right marks without a corresponding left mark within the same block.

Solution

Add the missing left mark within the same block to cross out text or start an inline note. If you want to use a combination of hyphen and plus sign or equals sign literally instead, prepend a backslash: \-+ or \-=.

Here is a minus-or-plus sign to copy and paste, in case you are looking for one: ∓