fractionalSeconds

Fractional-second digits. Matches FRACTIONAL_SECONDS regex: one or more digits. Every digit is significant and preserved, including leading and trailing zeros and an all-zero fraction: "05" (0.05 s) ≠ "5" (0.5 s), "120" is kept verbatim rather than normalized to "12", and "000" is kept rather than dropped to ensure even faulty encodings are round-tripped. Although cursed, certificates with such time encodings exist in practice.

When derived from an Instant, trailing zeros are stripped (DER minimum encoding). May carry more precision than instant's nanosecond resolution.