Analysis of information sources in references of the Wikipedia article "Matrix (printing)" in English language version.
the fitting of letter shapes to certain available widths, "duplexing", or the placing of a light and bold character on the same width
both designs had to measure the same width. This was called duplexing. If an italic was to be paired, or duplexed, with a roman, the italic was redrawn and refitted to the width of the roman.
A metal-type term referring to linecasting characters created to share matrices (the pieces of metal in which characters were cast) that consequently were designed to have exactly the same character widths (set widths). Typically, a roman typeface and its corresponding italic or a roman and a bold from the same typeface family might be designed to cross-rail duplex. When emulating typeface designs created for linecasting equipment, type designers need to be aware that the duplexing in these faces sometimes resulted in less than ideal spacing and/or character proportions in one or more of the typefaces that were duplexed.
A metal-type term referring to linecasting characters created to share matrices (the pieces of metal in which characters were cast) that consequently were designed to have exactly the same character widths (set widths). Typically, a roman typeface and its corresponding italic or a roman and a bold from the same typeface family might be designed to cross-rail duplex. When emulating typeface designs created for linecasting equipment, type designers need to be aware that the duplexing in these faces sometimes resulted in less than ideal spacing and/or character proportions in one or more of the typefaces that were duplexed.
