Delimiter characters are "||". Two types of call numbers are used: The current one and the old one.
The current rule for call numbers
Textbook classification numbers - publisher number - authorized years + book number (Ex. K170.8||K10||2010)
The old rule for call numbers
Textbook classification numbers - publisher number + administrative number - authorized / usage year (Ex. K260.91||S12U||01/05). Textbook classification, publisher number, administrative number and book number are originally assign by Education Library. Usage year is derived from the item holdings of Ducation Library, so some of the year might be different from the original usage year. If year numbers are four digits, they are Gregorian calendar years. In the other cases, the numbers from 21 to 64 corresponds to 1964 to 1989 (Showa Era), the ones from 88 to 99 are 1988 to 1999, and the ones from 00 to 05 means 2000 to 2005.