////
Included in:

- user-manual: Header
////

The revision information is read from the third (non-attribute) line of the header, beneath the author information line.
A document's revision information has slots for three implicit attributes.

[horizontal]
`revnumber`::
The document's version number.
In order to be recognized, the version number must contain at least one numeric character.
Any letters or symbols preceding the numeric character are ignored.
If the implicit `revnumber` is on a line by itself, it must begin with the "`v`" character (e.g., `v1.0`) or be followed by a comma (e.g., `1.0,`)
If the implicit `revdate` is present, it must be separated from the `revnumber` by a comma (e.g., `2020-10-10, v78.1`).

`revdate`::
The date the document version was completed.
When the `revnumber` or `revremark` attributes are set, but `revdate` is not, then `revdate` will be assigned the `docdate` value.

`revremark`::
Information about this version of the document.

Here's an example of a revision line.

[source]
----
include::ex-rev.adoc[tag=base]
----
<1> revnumber and revdate must be separated by a comma (`,`).
<2> revdate can contain words, letters, numbers, and symbols.
<3> The revremark attribute must be preceded by a colon (`:`), regardless of whether revnumber or revdate are set.

.Result: Rendered revision information displayed on the byline and referenced in the document's body
====
image::rev.png[Revision attributes]
====

The revnumber in the byline is prefixed by the word _Version_; however, when referenced in the body of the document, only the numerical value is displayed.
The `version-label` attribute controls the version number label in the byline.
The revision information attributes can also be explicitly set in the header.

[source]
----
include::ex-rev.adoc[tag=attr]
----
<1> When explicitly set, any characters preceding the version number are *not* dropped.
<2> The revremark can contain attribute references.
<3> The version-label attribute is unset so that the word _Version_ does not precede the revnumber in the byline.

.Result: Rendered revision information when revision attributes are explicitly set
====
image::rev-long.png[Explicitly set revision attributes]
====

In the converted document, notice that the _V_ preceding the revnumber is capitalized in the byline but not when the attribute is referenced in the body of the document.

NOTE: Revision extraction information and an extraction example are pending.
