blue – A doc­u­ment prepa­ra­tion sys­tem

The BLUe for­mat is a con­cise but ex­pres­sive doc­u­ment prepa­ra­tion sys­tem mod­elled on Knuth's man­mac; the for­mat is used in the au­thor’s “Pub­lish­ing with TeX”, which serves as a user man­ual for the for­mat. (The acronym is based on Knuth’s “Ben Lee User”, who tends to get sur­prised by things in ex­am­ples in the TeXbook.)