Standard ST.31

This recommended Standard provides character sets for the coding of patent documents for the purpose of exchange on machine‑readable records, e.g., on magnetic tape. The character sets include those characters, numerals and special symbols likely to be encountered during the processing of patent documents.

For the purposes of this recommended Standard the expression “patent document” comprises patents for invention, plant patents, inventors’ certificates, design patents, utility certificates, utility models, documents of addition thereto and published applications therefor.

The character sets are coded by means of a number of Code Pages. Each Code Page has a theoretical capacity of (16x16) 256 positions. In practice the first 64 positions of each Code Page are reserved for control codes, leaving a maximum of 192 positions usable for characters.

The character sets will be extended when new or previously unnecessary character sets or symbols become known. Moreover, further Code Pages will be elaborated to cover characters used in alphabets other than those defined in Code Pages 0, 1, 2, 3, 8 and 9.

In the tables accompanying each of the Code Pages, each of the codes provided for are defined by a print of the character concerned together with a description of the character. The code itself is quoted using two characters, the first character being the column of the code table with the second character being the row of the code table.

The mechanism for switching between Code Pages is an escape sequence in the data stream which indicates both that a switch must be performed and gives the identity of the Code Page (nn) required.

The selected Code Page remains active until a subsequent escape sequence is encountered indicating another Code Page.

However, switching to Code Page 9 would signal the start of two‑byte representation. To escape from Code Page 9, the appropriate (two‑byte) escape sequence must be used as follows: