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A bar or stroke is a modification consisting of a line drawn through a grapheme. It may be used as a diacritic to derive new letters from old ones, or simply as an addition to make a grapheme more distinct from others. It can take the form of a vertical bar, slash, or crossbar.
A stroke is sometimes drawn through the numerals 7 (horizontal overbar) and 0 (overstruck foreslash), to make them more distinguishable from the number 1 and the letter O, respectively. (In some typefaces, one or other or both of these characters are designed in these styles; they are not produced by overstrike or by combining diacritic. The normal way in most of Europe to write the number seven is with a bar. )
In medieval English scribal abbreviations, a stroke or bar was used to indicate abbreviation. For example, ⟨£⟩, the pound sign, is a stylised form of the letter ⟨Ꝉ⟩ (the letter ⟨L⟩ with a cross bar).
For the specific usages of various letters with bars and strokes, see their individual articles.
"The Origins of £sd". The Royal Mint Museum. Archived from the original on 8 March 2020. It is not known for certain when the horizontal line or lines, which indicate an abbreviation, first came to be drawn through the L. However, there is in the Bank of England Museum a cheque dated 7 January 1661 with a clearly discernible £ sign. By the time the Bank was founded in 1694 the £ sign was in common use.
