What is the difference between numbers that are “Unassigned” and numbers that are “Permanently unassigned”?
A number that is “Unassigned” is a deprecated number: it is currently invalid, though it was valid in the past. The number and the heading are in square brackets. Notes in the History box describe the changes that made the number invalid. For example:
It is unlikely that the deprecated number 363.42 will soon be reused for another topic—but it may eventually be reused. It is not permanently unassigned.
Incidentally, if you are not seeing records for “Unassigned” numbers in WebDewey and you want to see them, check the Preferences page to be sure that “Record Options” is set to show them:
A number that is “Permanently unassigned” is an optional number. The number and the heading are in parentheses. For example:
Currently, there are six optional numbers labeled “Permanently unassigned.” All those optional numbers are intended to meet local needs for organizing works on religion, or iconography of religion. All six numbers will remain permanently unassigned. The promise is that no standard DDC development will ever use those numbers, because that would inconvenience libraries using them as optional numbers.
Suggestions for use of “Permanently unassigned” numbers have changed over time. The note at 298 in DDC 17 (1965) said simply: “If it is desired to give local emphasis and a shorter number to a specific religion, class it here.” DDC 22 (2003) listed options A-E in the record for 290 Other religions:
(Options: To give preferred treatment or shorter numbers to a specific religion, use one of the following:
(Option A: Class the sources of the religion in 220, other specific aspects of the religion in 230-280, comprehensive works on the religion in 230; in that case class the Bible and Christianity in 298
(Option B: Class in 210, and add to base number 21 the numbers following the base number for the religion in 292-299, e.g., Hinduism 210, Mahabharata 219.23; in that case class philosophy and theory of religion in 200, its subdivisions 211-218 in 201-208, specific aspects of comparative religion in 200.1-200.9, standard subdivisions of religion in 200.01-200.09
(Option C: Class in 291, and add to base number 291 the numbers following the base number for that religion in 292-299, e.g., Hinduism 291, Mahabharata 291.923
(Option D: Class in 298, which is permanently unassigned
(Option E: Place first by use of a letter or other symbol, e.g., Hinduism 2H0 (preceding 220), or 29H (preceding 291 or 292); add to the base number thus derived, e.g., to 2H or to 29H, the numbers following the base number for the religion in 292-299, e.g., Shivaism 2H5.13 or 29H.513)
In DDC 22 the note at 298 read:
(Optional number used to provide local emphasis and a shorter number for a specific religion other than Christianity; prefer the number for the specific religion elsewhere in 292-299; or optional number used for Christianity if option A under 290 is chosen. Other options are described at 290)
Some librarians found the number of suggested options in 200 Religion confusing. After doing a survey in 2005 to see which of the options were being used the most, and with the support of the Editorial Policy Committee, the Dewey team reduced the number of suggestions for optional treatment, dropping option D. That does not mean, however, that libraries using 298 as recommended in option D in Edition 22 need to stop doing so. The suggestions are just suggestions; use of these optional numbers is up to the local library.