00:30 is only use in 24-hour clock. It is equivalent to 12:30 AM in 12-hour (AM/PM) clock. There is no such thing as 00:30 AM nor 00:30 PM.
Under the chapter confusion in Wiki:
It is not always clear what times "12:00 a.m." and "12:00 p.m." denote. From the
Latin words
meridies (midday),
ante (before) and
post (after), the term
ante meridiem (a.m.) means before midday and
post meridiem (p.m.) means after midday. Since "noon" (midday,
meridies (m.)) is neither before nor after itself, the terms a.m. and p.m. do not apply.
[2] Although "12 m." was suggested as a way to indicate noon, this is seldom done
[20] and also does not resolve the question of how to indicate midnight.
The American Heritage Dictionary of the English Language states "By convention,
12 AM denotes midnight and
12 PM denotes noon. Because of the potential for confusion, it is advisable to use
12 noon and
12 midnight."
[24]
E. G. Richards in his book
Mapping Time provided a diagram in which 12 a.m. means noon and 12 p.m. means midnight.
[25]
The style manual of the
United States Government Printing Office used 12 a.m. for noon and 12 p.m. for midnight until its 2008 edition, when it reversed these designations
[17][18] and then retained that change in its 2016 revision.
[26]
Many U.S. style guides, and
NIST's "Frequently asked questions (FAQ)" web page,
[2] recommend that it is clearest if one refers to "noon" or "12:00 noon" and "midnight" or "12:00 midnight" (rather than to "12:00 p.m." and "12:00 a.m."). The NIST website states that "12 a.m. and 12 p.m. are ambiguous and should not be used."
The Associated Press Stylebook specifies that midnight "is part of the day that is ending, not the one that is beginning."
[23]
The Canadian Press Stylebook[21] says, "write
noon or
midnight, not
12 noon or
12 midnight." Phrases such as "12 a.m." and "12 p.m." are not mentioned at all. Britain's National Physical Laboratory "FAQ-Time" web page
[22] states "In cases where the context cannot be relied upon to place a particular event, the pair of days straddling midnight can be quoted"; also "the terms 12 a.m. and 12 p.m. should be avoided."
Likewise, some U.S. style guides recommend either clarifying "midnight" with other context clues, such as specifying the two dates between which it falls, or not referring to the term at all. For an example of the latter method, "midnight" is replaced with "11:59 p.m." for the end of a day or "12:01 a.m." for the start of a day. That has become common in the United States in legal contracts and for
airplane,
bus, or
train schedules, though some schedules use other conventions. Occasionally, when trains run at regular intervals, the pattern may be broken at midnight by displacing the midnight departure one or more minutes, such as to 11:59 p.m. or 12:01 a.m.
[27]
In literature