|≈||approximately equal to|
|digits||indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …)|
The barleycorn is a small English unit of length equal to 1⁄3 of an inch (i.e., close to 0.8467 cm) still used in Great Britain and Ireland as a determiner of shoe sizes.
A twip (abbreviating "twentieth of a point", "twentieth of an inch point", or "twentieth of an Imperial point") is a typographical measurement, defined as 1/20 of a typographical point. One twip is 1/1440 inch or 17.639 µm.