Standard Abbreviation (ISO4): ISO 4 (Information and documentation – Rules for the abbreviation of title words and titles of publications) is an international standard which defines a uniform system for the abbreviation of serial publication titles, i.e., titles of publications such as scientific journals that are published in regular installments.
The International Organization for Standardization (ISO) has appointed the ISSN International Centre as the registration authority for ISO 4. It maintains the List of Title Word Abbreviations (LTWA), which contains standard abbreviations for words commonly found in serial titles.
A major use of ISO 4 is to abbreviate the names of scientific journals using the LTWA.
For instance, under ISO 4 standards, the The New England Journal of Medicine is cited as N. Engl. J. Med. (capitalization is not specified by the standard).
The standard notes that "Full stops shall only be used to indicate an abbreviation. Full stops may be omitted from abbreviated words in applications that require limited use of punctuation".