hhmmssmmm

hhmmssmmm is a compact, non-delimited time-stamp pattern that encodes hours, minutes, seconds, and milliseconds as a single string of digits. In this pattern, the digits appear in the order hour, minute, second, and millisecond, typically with two digits for hours, two for minutes, two for seconds, and three for milliseconds. The exact interpretation of the hour portion depends on the surrounding formatting rules: some contexts use a 12-hour clock, while others use a 24-hour clock. The three trailing digits are intended to represent milliseconds, yielding a precision of one millisecond.

This format is commonly used in logging, file naming, and other situations where a compact, sortable time representation is advantageous and where date information is handled separately. Because the fields occupy fixed widths, strings like 231530987 can be sorted lexicographically to reflect chronological order within a single day. However, hhmmssmmm does not convey date or time zone, so it cannot uniquely identify a moment across days without additional context. It is also sensitive to the chosen clock convention (12-hour vs. 24-hour) unless explicitly defined.

In programming practice, different environments use related patterns with different letter cases. For example, Java often uses HHmmssSSS to denote 24-hour hours, minutes, seconds, and milliseconds, while .NET uses HHmmssfff for the same idea. Python and other languages provide analogous constructs, typically requiring separate handling of the date and time zone. When adopting hhmmssmmm, it is important to document the exact interpretation, ensure consistent clock conventions, and consider adding date information or time-zone data to avoid ambiguity in multi-day or distributed contexts.