dwLowDateTime

dwLowDateTime is the name of the 32-bit field in the Windows FILETIME structure that stores the least significant 32 bits of a 64-bit timestamp. Combined with the adjacent dwHighDateTime field, it forms a 64-bit value representing the number of 100-nanosecond intervals since January 1, 1601 UTC (the FILETIME epoch). The full 64-bit value is obtained by shifting the high part left by 32 bits and OR-ing with the low part. On little-endian systems the two halves are stored in little-endian order, so the memory layout matches the natural endianness of Windows on x86/x64.

dwLowDateTime alone is not a time; its meaning arises when it is used in conjunction with dwHighDateTime to encode timestamps used by the Windows API. FILETIME values are used by functions such as GetSystemTimeAsFileTime, SetFileTime, and FileTimeToSystemTime to convert to and from other time representations. The 100-nanosecond unit provides high precision for file times and system times, but typical applications convert FILETIME values to more common representations like SYSTEMTIME, time_t, or ISO 8601 strings.

Notes: This representation uses the Windows epoch 1601-01-01, distinct from Unix epoch 1970-01-01. The 64-bit timestamp covers a very large range, making wraparound a practical concern only in far-future dates.