Replying to @⁨w8emv@a2mi.social⁩

@w8emv That's officially known as "square", but they note:

In some countries an alternative term (e.g. "hash", "pound" or "number sign") may be necessary for this purpose, particularly where the form in Figure 4 is commonly used

Square symbol with lines of equal length horizontal and vertical with overlaps at the ends — Open image attachment ⁨1⁩ of ⁨2⁩
Square symbol with lines of equal length horizontal and vertical with overlaps at the ends
Alternative square symbol with the vertical lines at an 80 degree angle rather than 90 degree — Open image attachment ⁨2⁩ of ⁨2⁩
Alternative square symbol with the vertical lines at an 80 degree angle rather than 90 degree