=head1 NAME
The name of your program or module.
=head1 SYNOPSIS
A one-line description of what your program or module does (purportedly).
=head1 DESCRIPTION
The bulk of your documentation. (Bulk is good in this context.)
=head1 AUTHOR
Who you are. (Or an alias, if you are ashamed of your program.)
=head1 BUGS
What you did wrong (and why it wasn’t really your fault).
=head1 SEE ALSO
Where people can find related information (so they can work around your bugs).
=head1 COPYRIGHT
The copyright statement. If you wish to assert an explicit copyright, you should say something like:
Copyright 2013, Randy Waterhouse. All Rights Reserved.
注意：每个=标签上下必须隔一行，否则就会错误解析。
=for html 或者 =for text
是把下面的单行注视当作html或者text来处理，与其功能类似的是 =begin html / =end html ; =begin text / =end text 两对。begin和end之间可以处理多行。
=over 4
=item SOMEWORD
*************
=item somewordelse
******
=back
以上写法是写一个列表，以over开头，后面的数字是列表中每行的缩进量。最后以=back 结尾。
=cut 是结束pod块的标志，与程序分开。
在perl中，可以使用 pod2html **.pm >**.html 来生成html格式的pod文档。
=pod =cut既可以作为程序多行注释，又可以实现程序usage说明，利用pod2text命令。die (`pod2text $0`);即可