class | R Documentation |

Recent extensions to standardised date notation in
ISO 8601-2_2019(E)
create space for unspecified, uncertain, and approximate dates,
as well as succinct representation of ranges of dates.
These functions create and validate a new date class for R
that can contain and parse these annotations,
and are not typically user-facing.
Please see `as_messydate()`

for the user-facing coercion function.

```
new_messydate(x = character())
validate_messydate(x)
```

`x` |
A character scalar or vector in the expected |

*Unspecified date components*, such as when the day is unknown,
can be represented by one or more `X`

s in place of the digits.
The modifier `*`

is recommended to indicate that the entire
time scale component value is unspecified, e.g. `X*-03-03`

,
however this is not implemented here.
Please be explicit about the digits that are unspecified,
e.g. `XXXX-03-03`

expresses 3rd March in some unspecified year,
whereas `2003-XX-03`

expresses the 3rd of some month in 2003.
If time components are not given, they are expanded to this.

*Approximate date components*, modified by `~`

,
represent an estimate whose value is asserted
to be possibly correct.
For example, `2003~-03-03`

The degree of confidence in approximation
depends on the application.

*Uncertain date components*, modified by `?`

,
represent a date component whose source is considered
to be dubious and therefore not to be relied upon.
An additional modifier, `%`

, is used to indicate
a value that is both uncertain and approximate.

These functions also introduce standard notation
for ranges of dates.
Rather than the typical R notation for ranges,
`:`

, ISO 8601-2_2019(E) recommends `..`

.
This then can be applied between two time scale
components to create a standard range between
these dates (inclusive), e.g. `2009-01-01..2019-01-01`

.
But it can also be used as an affix,
indicating "on or before" if used as a prefix,
e.g. `..2019-01-01`

,
or indicating "on or after" if used as a suffix,
e.g. `2009-01-01..`

.

And lastly, notation for sets of dates is also included.
Here braces, `{}`

, are used to mean "all members of the set",
while brackets, `[]`

, are used to mean "one member of the set".

Object of class `mdate`

messydate

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