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+=head1 NAME
+
+version - Perl extension for Version Objects
+
+=head1 SYNOPSIS
+
+ # Parsing version strings (decimal or dotted-decimal)
+
+ use version 0.77; # get latest bug-fixes and API
+ $ver = version->parse($string)
+
+ # Declaring a dotted-decimal $VERSION (keep on one line!)
+
+ use version; our $VERSION = version->declare("v1.2.3"); # formal
+ use version; our $VERSION = qv("v1.2.3"); # shorthand
+ use version; our $VERSION = qv("v1.2_3"); # alpha
+
+ # Declaring an old-style decimal $VERSION (use quotes!)
+
+ our $VERSION = "1.0203"; # recommended
+ use version; our $VERSION = version->parse("1.0203"); # formal
+ use version; our $VERSION = version->parse("1.02_03"); # alpha
+
+ # Comparing mixed version styles (decimals, dotted-decimals, objects)
+
+ if ( version->parse($v1) == version->parse($v2) ) {
+ # do stuff
+ }
+
+ # Sorting mixed version styles
+
+ @ordered = sort { version->parse($a) <=> version->parse($b) } @list;
+
+=head1 DESCRIPTION
+
+Version objects were added to Perl in 5.10. This module implements version
+objects for older version of Perl and provides the version object API for all
+versions of Perl. All previous releases before 0.74 are deprecated and should
+not be used due to incompatible API changes. Version 0.77 introduces the new
+'parse' and 'declare' methods to standardize usage. You are strongly urged to
+set 0.77 as a minimum in your code, e.g.
+
+ use version 0.77; # even for Perl v.5.10.0
+
+=head1 TYPES OF VERSION OBJECTS
+
+There are two different types of version objects, corresponding to the two
+different styles of versions in use:
+
+=over 2
+
+=item Decimal Versions
+
+The classic floating-point number $VERSION. The advantage to this style is
+that you don't need to do anything special, just type a number into your
+source file. Quoting is recommended, as it ensures that trailing zeroes
+("1.50") are preserved in any warnings or other output.
+
+=item Dotted Decimal Versions
+
+The more modern form of version assignment, with 3 (or potentially more)
+integers separated by decimal points (e.g. v1.2.3). This is the form that
+Perl itself has used since 5.6.0 was released. The leading 'v' is now
+strongly recommended for clarity, and will throw a warning in a future
+release if omitted. A leading 'v' character is required to pass the
+L</is_strict()> test.
+
+=back
+
+=head1 DECLARING VERSIONS
+
+If you have a module that uses a decimal $VERSION (floating point), and you
+do not intend to ever change that, this module is not for you. There is
+nothing that version.pm gains you over a simple $VERSION assignment:
+
+ our $VERSION = "1.02";
+
+Since Perl v5.10.0 includes the version.pm comparison logic anyways,
+you don't need to do anything at all.
+
+=head2 How to convert a module from decimal to dotted-decimal
+
+If you have used a decimal $VERSION in the past and wish to switch to a
+dotted-decimal $VERSION, then you need to make a one-time conversion to
+the new format.
+
+B<Important Note>: you must ensure that your new $VERSION is numerically
+greater than your current decimal $VERSION; this is not always obvious. First,
+convert your old decimal version (e.g. 1.02) to a normalized dotted-decimal
+form:
+
+ $ perl -Mversion -e 'print version->parse("1.02")->normal'
+ v1.20.0
+
+Then increment any of the dotted-decimal components (v1.20.1 or v1.21.0).
+
+=head2 How to C<declare()> a dotted-decimal version
+
+ use version; our $VERSION = version->declare("v1.2.3");
+
+The C<declare()> method always creates dotted-decimal version objects. When
+used in a module, you B<must> put it on the same line as "use version" to
+ensure that $VERSION is read correctly by PAUSE and installer tools. You
+should also add 'version' to the 'configure_requires' section of your
+module metadata file. See instructions in L<ExtUtils::MakeMaker> or
+L<Module::Build> for details.
+
+B<Important Note>: Even if you pass in what looks like a decimal number
+("1.2"), a dotted-decimal will be created ("v1.200.0"). To avoid confusion
+or unintentional errors on older Perls, follow these guidelines:
+
+=over 2
+
+=item *
+
+Always use a dotted-decimal with (at least) three components
+
+=item *
+
+Always use a leading-v
+
+=item *
+
+Always quote the version
+
+=back
+
+If you really insist on using version.pm with an ordinary decimal version,
+use C<parse()> instead of declare. See the L<PARSING AND COMPARING VERSIONS>
+for details.
+
+See also L<version::Internals> for more on version number conversion,
+quoting, calculated version numbers and declaring developer or "alpha" version
+numbers.
+
+=head1 PARSING AND COMPARING VERSIONS
+
+If you need to compare version numbers, but can't be sure whether they are
+expressed as numbers, strings, v-strings or version objects, then you should
+use version.pm to parse them all into objects for comparison.
+
+=head2 How to C<parse()> a version
+
+The C<parse()> method takes in anything that might be a version and returns
+a corresponding version object, doing any necessary conversion along the way.
+
+=over 2
+
+=item *
+
+Dotted-decimal: bare v-strings (v1.2.3) and strings with more than one
+decimal point and a leading 'v' ("v1.2.3"); NOTE you can technically use a
+v-string or strings with a leading-v and only one decimal point (v1.2 or
+"v1.2"), but you will confuse both yourself and others.
+
+=item *
+
+Decimal: regular decimal numbers (literal or in a string)
+
+=back
+
+Some examples:
+
+ $variable version->parse($variable)
+ --------- -------------------------
+ 1.23 v1.230.0
+ "1.23" v1.230.0
+ v1.23 v1.23.0
+ "v1.23" v1.23.0
+ "1.2.3" v1.2.3
+ "v1.2.3" v1.2.3
+
+See L<version::Internals> for more on version number conversion.
+
+=head2 How to check for a legal version string
+
+If you do not want to actually create a full blown version object, but
+would still like to verify that a given string meets the criteria to
+be parsed as a version, there are two helper functions that can be
+employed directly:
+
+=over 4
+
+=item C<is_lax()>
+
+The lax criteria corresponds to what is currently allowed by the
+version parser. All of the following formats are acceptable
+for dotted-decimal formats strings:
+
+ v1.2
+ 1.2345.6
+ v1.23_4
+ 1.2345
+ 1.2345_01
+
+=item C<is_strict()>
+
+If you want to limit yourself to a much more narrow definition of what
+a version string constitutes, C<is_strict()> is limited to version
+strings like the following list:
+
+ v1.234.5
+ 2.3456
+
+=back
+
+See L<version::Internals> for details of the regular expressions
+that define the legal version string forms, as well as how to use
+those regular expressions in your own code if C<is_lax()> and
+C<is_strict()> are not sufficient for your needs.
+
+=head2 How to compare version objects
+
+Version objects overload the C<cmp> and C<< <=> >> operators. Perl
+automatically generates all of the other comparison operators based on those
+two so all the normal logical comparisons will work.
+
+ if ( version->parse($v1) == version->parse($v2) ) {
+ # do stuff
+ }
+
+If a version object is compared against a non-version object, the non-object
+term will be converted to a version object using C<parse()>. This may give
+surprising results:
+
+ $v1 = version->parse("v0.95.0");
+ $bool = $v1 < 0.96; # FALSE since 0.96 is v0.960.0
+
+Always comparing to a version object will help avoid surprises:
+
+ $bool = $v1 < version->parse("v0.96.0"); # TRUE
+
+Note that "alpha" version objects (where the version string contains
+a trailing underscore segment) compare as less than the equivalent
+version without an underscore:
+
+ $bool = version->parse("1.23_45") < version->parse("1.2345"); # TRUE
+
+See L<version::Internals> for more details on "alpha" versions.
+
+=head1 OBJECT METHODS
+
+=head2 is_alpha()
+
+True if and only if the version object was created with a underscore, e.g.
+
+ version->parse('1.002_03')->is_alpha; # TRUE
+ version->declare('1.2.3_4')->is_alpha; # TRUE
+
+=head2 is_qv()
+
+True only if the version object is a dotted-decimal version, e.g.
+
+ version->parse('v1.2.0')->is_qv; # TRUE
+ version->declare('v1.2')->is_qv; # TRUE
+ qv('1.2')->is_qv; # TRUE
+ version->parse('1.2')->is_qv; # FALSE
+
+=head2 normal()
+
+Returns a string with a standard 'normalized' dotted-decimal form with a
+leading-v and at least 3 components.
+
+ version->declare('v1.2')->normal; # v1.2.0
+ version->parse('1.2')->normal; # v1.200.0
+
+=head2 numify()
+
+Returns a value representing the object in a pure decimal form without
+trailing zeroes.
+
+ version->declare('v1.2')->numify; # 1.002
+ version->parse('1.2')->numify; # 1.2
+
+=head2 stringify()
+
+Returns a string that is as close to the original representation as possible.
+If the original representation was a numeric literal, it will be returned the
+way perl would normally represent it in a string. This method is used whenever
+a version object is interpolated into a string.
+
+ version->declare('v1.2')->stringify; # v1.2
+ version->parse('1.200')->stringify; # 1.200
+ version->parse(1.02_30)->stringify; # 1.023
+
+=head1 EXPORTED FUNCTIONS
+
+=head2 qv()
+
+This function is no longer recommended for use, but is maintained for
+compatibility with existing code. If you do not want to have it exported
+to your namespace, use this form:
+
+ use version 0.77 ();
+
+=head2 is_lax()
+
+(Not exported by default)
+
+This function takes a scalar argument and returns a boolean value indicating
+whether the argument meets the "lax" rules for a version number. Leading and
+trailing spaces are not allowed.
+
+=head2 is_strict()
+
+(Not exported by default)
+
+This function takes a scalar argument and returns a boolean value indicating
+whether the argument meets the "strict" rules for a version number. Leading
+and trailing spaces are not allowed.
+
+=head1 AUTHOR
+
+John Peacock E<lt>jpeacock@cpan.orgE<gt>
+
+=head1 SEE ALSO
+
+L<version::Internals>.
+
+L<perl>.
+
+=cut