modifier is the correct component to contain an optional label like beta.

The modifier is intended for non numeric qualifiers and pre release or metadata labels. In Calendar Versioning the numeric parts represent the date and release sequence and the modifier lets you append identifiers such as beta or rc without altering the chronological meaning of the numeric components.

micro is a numeric patch level and it is not used for textual labels. Placing a label in the patch position would confuse sorting and the intended meaning of micro as small revisions.

major represents the primary date or year component in CalVer and it must remain numeric. Labels do not belong there because that would break the date based semantics of the version string.

minor is the secondary numeric release counter and it is also not for optional textual labels. The modifier is the proper place for identifiers like beta so that numeric components stay machine sortable and meaningful.

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