Vertical bar
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The vertical bar, |, is a glyph with various uses in mathematics, computing, and typography. It has many names, often related to particular meanings: Sheffer stroke, pipe, bar, or, vbar, and others.
US International keyboard showing broken bar on the keycap, even though pressing ⇧ Shift+\ produces the solid vertical bar.
Pilcrow
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The pilcrow, ¶, is a handwritten or typographical character used to identify a paragraph. It is also called the paragraph mark, paraph, or blind P.
Three short paragraphs on making gunpowder in the manuscript GNM 3227a (Germany, c. 1400); the first paragraph is marked with an early form of the pilcrow sign, the two following paragraphs are introduced with litterae notabiliores (literally: enlarged letters).
Pilcrow signs in an excerpt from a page of Villanova, Rudimenta Grammaticæ, printed by Spindeler in 1500 in Valencia.
Opening page of Genesis from the Doves Bible (Doves Press, 1902): pilcrow used as a verse marker