proposes to do all arithmetic on the 128-bit number, converting it to a single 20-digit base-85 number (internal whitespace not allowed), rather than breaking it into four 32-bit groups. The proposed character set is, in order, 0–9, A–Z, a–z, and then the 23 characters !#$%&()*+-;<=>?@^_`{|}~. The highest possible representable address, 2128−1 = 74×8519 + 53×8518 + 5×8517 + ..., would be encoded as =r54lj&NUUO~Hi%c2ym0. This character set excludes the characters "',./:[\] , making it suitable for use in JSON strings (where " and \ would require escaping). However, for SGML-based protocols, notably including XML, string escapes may still be required (to accommodate <, > and &). See also Base32 Base36 Base64 Binary-to-text encoding for a comparison of various encoding algorithms PostScript Standard Encoding References External links BasE91 PostScript Language Reference (Adobe) - see ASCII85Encode Filter Binary-to-text encoding formats