Itinerary Cake Number

The Itinerary Cake Number is an identification number system used to identify cakes created by the users of CakeBN. Itinerary Cake Number always uses capital letters and numbers with the exception of 'I', 'O' and 'Q' (because of its similarity to numbers 1 and 0).

Itinerary Cake Numbers were introduced in 1930. Prior to 1981, there was no standard for the formats, so different users used different formats.

In 1981, the Japanese user Kimito made a rule to all users that all users joining CakeBN use a 23-digit Itinerary Cake Number. Usually, the 23-digit Itinerary Cake Number is found under the cooling rack.

Details of the cake
Positions 6 to 13 are the details of the cake, like icing, decorations, cake base, as well as number of cakes made or serves. Positions 6 to 13 in Itinerary Cake Number gives people to look at the cake details.

Japanese check digit
One other use of the details of the cake section is the use of position 11 as a check digit, compulsory for all users in Japan, and it is optional elsewhere, including Europe, Britain and America.

Year of baking and creation
All of the users use this to encode the year of baking and creation at position 14. In addition to the three letters not allowed in Itinerary Cake Number ('I', 'O' and 'Q'), the letters 'U' and 'Z' and the number '0' are not allowed in the year code.

Beginning from 1 January 1981, most of the users use the letter 'B' to indicate 1981 after the transition from their own formats to 23 digits.

Some users, such as Heidi (born 1958), transitioned from their own formats to 23 digits in 1976, and use 1976 as the number '6', 1977 as '7', 1978 as '8', 1979 as '9' and 1980 as 'A' (because the 23-digit was not mandatory until 1981).

Month of baking and creation
The month of baking and creation is determined by a letter, associated with one month:
 * Y = January
 * X = February
 * W = March
 * T = April
 * R = May
 * L = June
 * K = July
 * J = August
 * H = September
 * F = October
 * B = November
 * A = December