This is a usage question that may or may not be relevant to mathematics. However, as the representative to the Unicode Technical Committee for the STIX project [*], which involved adding mathematical and technical symbols to Unicode, I have been asked for information regarding several symbols that were accepted as part of this effort, and require expert assistance.
The symbols in question are the square brackets with ticks, that appear with Unicodes U+298D..U+2990:
Are these brackets used in mathematics, and if not, in what subject area(s) might they be used?
Which brackets are paired? (My inclination is that U+298D pairs with U+298E, and U+298F with U+2990, setting up a visual diagonal.)
If used in mathematics, in what field(s) are they used, and with what meaning(s)?
Can someone provide a published example of usage?