ISO 4 abbreviation of "Journal of Computational Physics: X" [closed]
Assuming that https://www.slideshare.net/agelsorin/iso-00004-1997 is accurate, section 4.6 of ISO 4:1997 reads:
The punctuation which occurs in the full title shall be retained in the abbreviated title with the exception of commas and full stops (periods); commas shall be omitted in the abbreviated title and full stops shall be replaced by commas. However, full stops may be retained in the abbreviated title when they are used with acronyms, initialisms, ordinal numbers or dependent title designations.
Full stops shall only be used to indicate an abbreviation. Full stops may be omitted from abbreviated word in applications that require limited use of punctuation.
By this logic, the colon stays a colon and "Journal of Computational Physics: X" is abbreviated as "J. Comput. Phys.: X"