Normally Roll20 expresses time in GMT +1 . However it also expresses it in AM and PM . Now this is fine if its a time like 1:00 PM or something , but the definition of 12:00 Pm or AM changes according to where you are. Is 12:00 PM Midnight or is it Noon , according to roll20 time? This may even differ from the convention given below. <a href="https://en.wikipedia.org/wiki/12-hour_clock" rel="nofollow">https://en.wikipedia.org/wiki/12-hour_clock</a> from wikipedia 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 strictly speaking "noon" (midday - meridies (m.)) is neither before nor after itself, the terms a.m. and p.m. do not apply. [17] Although "12 m." would be a logically consistent way to indicate noon, this is seldom done (and so risks misunderstanding), and it does not resolve the question of how to indicate midnight. The American Heritage Dictionary of the English Language has a usage note on this topic: "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." [18] E. G. Richards in his book Mapping Time provided a diagram in which 12 a.m. means noon and 12 p.m. means midnight. [19] Many U.S. style guides, and NIST 's "Frequently asked questions (FAQ)" web page, [17] 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 explicitly states that "12 a.m. and 12 p.m. are ambiguous and should not be used." The Canadian Press Stylebook (11th Edition, 1999, page 288) 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 [20] 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 midnight 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 23:59 or 00:01. [21] The 24-hour clock notation avoids these ambiguities by using 00:00 for midnight at the start of the day and 12:00 for noon and 24:00 for midnight at the end of a day. In Britain, various conventions are employed. For instance, on 17 December 2005 The Sun (London) newspaper's TV magazine used "noon (12.00)" and "midnight (0.00)" in individual listings. Sequential listings started with a.m. or p.m. as appropriate, but these indicators were not used again, although in sub-listings "12midnight" was sometimes employed. On the same date, London's The Daily Telegraph used "12.00noon" and "12.00midnight" in individual listings. In sequential listings the first programme to start after 12.00 was marked "am" or "pm" as appropriate.