Mercedonius

Identify the calendar role

Mercedonius denotes a Roman intercalary month inserted in the February sequence to help align the calendar with the seasons. Source: [Lex: mercedonius](https://lex.dk/mercedonius).

1. Does this reference denote the Roman intercalary month, or merely mention its name in another context? definition
2. Which historical calendar phase does the reference concern? boundary

Qualify name equivalence

Historical dictionary material associates Mercedonius and Mercedinus with the intercalary month; the model should retain the wording and witness behind each identification. Source: [CLD: mercedonius](https://cld.bbaw.de/lemma/lat/mercedonius).

1. What exact spelling and language occur in the cited witness? provenance
2. What evidence supports treating this designation as equivalent to the registry's Mercedonius? definition

Preserve boundary variants

Accounts place intercalation after February 23 or 24 and explain its relationship to February's remaining days differently; retain the chosen account rather than silently standardizing it. Source: [Encyclopaedia Romana: Intercalation](https://penelope.uchicago.edu/~grout/encyclopaedia_romana/calendar/intercalation.html).

1. After which February date does this source place the insertion? boundary
2. How does this account assign the remaining February days to the intercalary sequence? definition

Reconcile duration statements

A historical reference distinguishes 22 or 23 inserted days from 27 or 28 when five remaining February days are included. These are source-specific counting statements, not interchangeable measurements. Source: [Smith's Dictionary: Calendarium](https://penelope.uchicago.edu/Thayer/E/Roman/Texts/secondary/SMIGRA%2A/Calendarium.html).

1. Does the stated length measure the year's net extension or the full counted intercalary interval? measurement
2. Does the reconstructed day sequence reproduce the stated year length without counting February days twice? measurement

Separate cycle from decision

Record cycle descriptions, attributed authority, and evidence of implementation separately. Historical accounts themselves leave uncertainty about whether some proposed cycles were strictly followed. Source: [The Galileo Project: Gregorian Calendar](https://galileo.library.rice.edu/chron/gregorian.html).

1. Does the source describe an ideal cycle, a customary practice, or a decision for a named year? definition
2. Which testimony identifies who could authorize or announce this intercalation? provenance

Assess an occurrence

Each proposed occurrence should retain its Roman year identification, supporting evidence, reconstruction assumptions, and unresolved alternatives.

1. What dated document, calendar witness, or historical testimony supports presence or absence in this year? provenance
2. Should the agent classify this occurrence as attested, reconstructed, disputed, or unknown? action

Gate exact conversion

An exact conversion requires a specified year, intercalation reconstruction, date-counting convention, target calendar, and sufficient chronological anchors.

1. Which independent anchor constrains the correspondence between this Roman date and the target calendar? provenance
2. Do the surviving alternatives permit one date, several candidate dates, or no defensible conversion? action

Distinguish replacement mechanisms

The Julian reform replaced the earlier calendar arrangement with a solar-year system using an intercalary day. A calendar correction must therefore be identified by mechanism and period before it is assigned to Mercedonius. Source: [The Galileo Project: Gregorian Calendar](https://galileo.library.rice.edu/chron/gregorian.html).

1. Is this reference to the February intercalary month, an exceptional reform interval, or a Julian intercalary day? boundary
2. Should the agent apply this model, preserve an uncertain identification, or refer the operation to the relevant calendar model? action

Check these first

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these check these first hold for the sense of Mercedonius this model covers, and on what evidence? provenance

Real-world use

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these real-world use hold for the sense of Mercedonius this model covers, and on what evidence? provenance

Typical measurements

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these typical measurements hold for the sense of Mercedonius this model covers, and on what evidence? provenance

Failure modes and hazards

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these failure modes and hazards hold for the sense of Mercedonius this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of Mercedonius this model covers, and on what evidence? provenance