The rules for serial (and monographic series) title changes are subdivided into “major” and “minor” changes. For serials, a major change requires a new bibliographic record. A minor change is generally handled by updating the existing record with a 246 field. For series statements, a major change requires a new series authority record; a minor change is generally handled with a reference (4XX) on the SAR.
In RDA, major changes to the title proper can be found under RDA 220.127.116.11.1 and the corresponding LC-PCC PS. Under AACR2 changes to title proper were covered under 21.2A and the corresponding LC rule interpretation (LCRI).
LC-PCC PS Major-Minor Changes in the Titles Proper of Serials. General Guidelines. [Section in PS preceding LC-PCC PS 18.104.22.168.1]
1. RDA instructions 22.214.171.124 and 126.96.36.199 apply to serials, series, and series-like phrases.
2. Base decisions on title changes on a comparison of the titles proper; do not use a variant title as the basis for title changes in serials or series.
3. "Multiple minor changes in the title do not equal a major change."
Most changes requiring a new record involve the title proper (for serials, 245 ‡a and ‡p; for series 490 ‡a [490 does not have a subfield for parts]. Per RDA 188.8.131.52.1 (formerly AACR2 21.2A1), a major change in the title proper is considered to be
a. the addition, deletion, change, or reordering of any of the first five words (the first six words if the title beings with an article) unless the change belongs to one or more of the categories listed in RDA 184.108.40.206.2 (Minor Changes)
b. the addition, deletion, or change of any word after the first five words (the first six words if the title begins with an article) that changes the meaning of the title or indicates a different subject matter
c. a change of name for a corporate body included anywhere in the title if the changed name is for a different corporate body [i.e. the corporate body name would have a separate authority record].
RDA 220.127.116.11.2 covers minor changes to the title proper. Minor changes in AACR2 were under 21.2A2; there are only minor differences in wording)
a) a difference in the representation of a word or words anywhere in the title (e.g., one spelling vs. another; abbreviated word or sign or symbol vs. spelled-out form; arabic numeral(s) vs. roman numeral(s); numbers or dates vs. spelled-out form; hyphenated words vs. unhyphenated words; one-word compounds vs. two-word compounds, whether hyphenated or not; an acronym or initialism vs. full form; or a change in grammatical form (e.g., singular vs. plural))
LC-PCC PS 18.104.22.168.2 Category A (formerly LCRI 21.2A2). "Consider that "one spelling vs. another" applies both in the case of ordinary orthographic variations and in the case of official orthographic changes. Consider that "a change in grammatical form" includes singular vs. plural, adjective vs. noun, and genitive vs. nominative case."
b) the addition, deletion, or change of articles, prepositions, or conjunctions anywhere in the title
c) a difference involving the name of the same corporate body and elements of its hierarchy or their grammatical connection anywhere in the title (e.g., the addition, deletion, or rearrangement of the name of the same corporate body or the substitution of a variant form
LC-PCC PS 22.214.171.124. Category C. "If the change is in the name of a body that is part of the title proper and the change requires the creation of a new heading for the body (see RDA 126.96.36.199), consider such a change to be a major change. Consider the presence or absence of the name or title of the official of the body to be a minor change. Consider the presence or absence of the body to whom a publication is presented to be a minor change."
d) the addition, deletion, or change of punctuation, including initialisms and letters with separating punctuation vs. those without separating punctuation, anywhere in the title
e) a different order of titles when the title is given in more than one language in the chief source of information, provided that the title chosen as title proper still appears as a parallel title
LC-PCC PS 188.8.131.52. Category E. "Also apply this category when the title is given in more than one script. Do not consider there to be a major change even if the addition of the title in another language or script on a later issue would affect the choice of title proper if the description were based on that issue. However, consider that there has been a major change if there is evidence that the publisher intentionally changed the title; such evidence may include, for example, a statement by the publisher or a new ISSN printed on the publication."
f) the addition, deletion, or change of words anywhere in the title that link the title to the numbering
g) two or more titles proper used on different issues of a serial according to a regular pattern
LC-PCC PS 184.108.40.206. Category G. "Also apply this category when the language of the title varies according to the language of the text. However, consider that there has been a major change if there is evidence that the publisher intentionally changed the title; such evidence may include, for example, a statement by the publisher or a new ISSN printed on the publication."
h) the addition to, deletion from, or change in the order of words in a list anywhere in a title, provided that there is no significant change in the subject matter
LC-PCC PS 220.127.116.11. Category H.: "Consider that "a list" means at least three terms."
i) the addition, deletion, or rearrangement anywhere in the title of words that indicate the type of resource such as "magazine," "journal," or "newsletter" or their equivalent in other languages. ["rearrangement" was formerly only in the LCRI; it is now part of the rules]
LC-PCC PS 18.104.22.168. Category I. "The change from one word to another (e.g., the change from "magazine" to "journal") is a major change. The word "series" does indicate a type of resource. A word denoting frequency (e.g., "monthly") does not indicate a type of resource."
RDA 22.214.171.124.2 (last sentence): In case of doubt, consider the change to be a minor change.