Numerous resources indicate that preferences regarding the inclusion of leading zeroes in clocks (
8:42 in 24-hr clocks;
03:42 p.m. vs.
3:42 p.m. in 12-hr clocks) may be unique to individual markets / countries. Yet it is frustratingly hard to locate comprehensive resources on what these preferences are on a per-country basis.
My question is -- what are these preferences by country (for major markets)? Do comprehensive resources exist on these preferences?
Evidence Such Preferences Exist
A table by Aaron Marcus, indicates that there are preferences in leading zeroes in clock display that are societal preferences often on a per-time bases:
(This table is shown in "Human-Computer Interaction: Design Issues, Solutions, and Applications" : "Chapter 2: Global/Intercultural User Interface Design" (author: Aaron Marcus) pg 31 and "Human Computer Interaction Handbook: Fundamnetals, Evolving Technologies, and Emerging Applications 3rd Ed." :"Chapter 15: Globalization, Localization, and Cross-Cultural User-Interface Design" (author: Aaron Marcus and Emilie W. Gould) pg 354)
This suggests that there is indeed such a preference on a per country basis and that it is perhaps independent from preference of 12-hour vs. 24-hour clock. (And hence that it may be desirable to localize whether to pad with leading zeros or not pad regardless of whether the mode is 12-hr or 24-hr.)
Further evidence that differences in padding preferences are determinable by country is found in a Wikipedia article "Date and Time Notations in Europe" which asserts:
Just as with the date format, leading zeros seem to be less common in [clocks in] Germany than in Austria and Switzerland...
(Analyzing the non-English source is challenging as it is no longer available from the linked page.)
I see in general the topic is treated by the coding community in a couple of ways:
Leave it up to the user
My feeling is that this flexibility is arguably a good thing for certain applications, but the decided downside is it gives no attempt to give the developer default behavior respecting local market preferences, hence leaving it to developers to try to formulate their own localizations.
Note: some standards adopt this sort of laissez-faire perspective as well -- Unix's strptime standard (v2, (c) 1997) for instance proclaims that
leading zeros are permitted but not required.
Force the user to do what we think is best
One of the more popular standards for 24-hour clocks in Europe is ISO 8601 which mandates padding with leading zeroes to two digits.
The disadvantage here (in my view) is that market preferences may be ignored. For devices with no pre-digital clock feature -- the phone for instance -- this may be somewhat less of a problem. For other devices including transportation consoles (aircraft, cars, etc.) that had clocks in the pre-digital face this in my view is more problematic as you're not only disregarding the colloquial local preference, you're likely disregarding the behavior of your target in the pre-digital era.
This is often justified by the argument that it is "more logical" to display a leading zero to cue the user that the time they're seeing is a 24-hour time and not an ambiguous time in 12-hr format with the "A.M."/"P.M." identifier missing. However, even if the assumption that the leading zero helps users identify a 24-hour clock is generally correct, it fails to fix other ambiguity problems such as those observed when the clock reads
What Do Users in Specific Countries Prefer?
My preference would be to default to the localized preference in my UI, but I need help locating comprehensive resources discussing preference padding with leading zeros by country.
In general a paradigm of UI design is to tailor your UI per the conventions of your target audience. The classic instance of this is whether to use a 12 hour depiction of time versus a 24 hour one. Various tables have been proposed for on a per-country basis which is most appropriate.
The passages above a similar country-based preference table could be formulated for leading zero preferences -- the question is has it?
I'm not looking to be told "just use ISO 8601" because while that may be some professionals' perspective, it does not answer the question topic of providing resources to determine preference by country for padding w/ leading zeros.
If such a compilation does not exist, alternatively it would be valid to propose here based on individual resources indicating preference for a specific country.
I removed the anecdotal about clock faces in OS X as it was pointed out it was discussing more of an unusual use of leading zeroes in a