There are various reasons to generate the hyphenation
at output by programming:

1. To reduce work at input, by reducing number of characters
2. To eliminate manual checking of hyphenation
3. To ensure accuracy of format in all ISMN listings and
   publications (regardless of the format submitted by the publisher)

For correct presentation, the letter M and the 9 digits of an ISMN must be divided, by hyphens, into four parts:

• Part 1: Distinguishing element: Constant "M"
• Part 2: The publisher identifier
• Part 3: The item identifier
• Part 4: The check digit

The position of the hyphens are determined by the publisher prefix range. The knowledge of the prefix ranges is necessary to develop the hyphenation output program.

The publisher prefix ranges are as follows:

Publisher Identifier    Total numbers available 
                        for item identificaton
--------------------    -----------------------
    000----099                 100000
   1000----3999                 10000
  40000----69999                 1000
 700000----899999                 100
9000000----9999999                 10


                            If Number
Publisher Identifier    Ranges are Between          Insert Hyphens After 
--------------------    ------------------    --------------------------------
    000----099              00-09             1st digit(M) 4th digit   9th digit
   1000----3999             10-39               "          5th digit     "
  40000----69999            40-69               "          6th digit     "
 700000----899999           70-89               "          7th digit     "
9000000----9999999          90-99               "          8th digit     "