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Diffstat (limited to 'lib/kernel/rite.mli')
| -rw-r--r-- | lib/kernel/rite.mli | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/lib/kernel/rite.mli b/lib/kernel/rite.mli index 39538d0..0dcf17e 100644 --- a/lib/kernel/rite.mli +++ b/lib/kernel/rite.mli @@ -17,6 +17,33 @@ type ('s, 'r) t = { into rite-agnostic code and be silently wrong for a Julian-reckoning rite. Read by {!Layer.index} to resolve {!Date_spec.Easter_offset}. *) + fixed_key : Date.t -> (int * int) option; + (** The (month, day) under which a FIXED sanctoral entry ({!Layer.on_date}) + is looked up for this civil date. [Some (month, day)] identity for + every rite with no reason to differ -- a Byzantine or other + non-Roman rite supplies nothing beyond that, and its output is + therefore byte-identical to a rite that predates this field + entirely. [None] means no fixed entry can ever be found for this + date, regardless of what {!Layer.index} holds. + + Exists for the Roman calendarium's own bissextile (leap-year) + footnote (February, docs/research/LT.txt:5011-5014): the + intercalary day is inserted by DOUBLING the sixth kalends of March + (civil 24 February in a common year), not by appending a 29th day + at the month's end, so every fixed feast dated at or after that + kalends position is kept one civil day later than usual, and 24 + February itself carries no fixed entry that year. This is a fact + about the ROMAN rite's own kalends reckoning, not a universal + computus rule -- a rite with no such convention (or none at all, + the default above) must not have it hardcoded into rite-agnostic + code, the same reason {!easter} above is rite-supplied rather than + chosen here. See rite_ef/temporal_ef.ml's [bissextile_fixed_key] + for the concrete Roman implementation and its full citation. + + Deliberately untouched: the MOVABLE half of {!Layer.on_date}'s + lookup ({!Date_spec.Easter_offset}, {!Date_spec.Nth_weekday}) -- + this field's contract is fixed-date reckoning only, and nothing in + the calendarium footnote concerns Easter-relative dates. *) rules : ('s, 'r) Precedence.rules; season_runs : 's list; (** the expected run-length-compressed season sequence over one liturgical |