NAME

       Pandoc::Metadata - pandoc document metadata

DESCRIPTION

       Document metadata such as author, title, and date can be embedded in different documents
       formats. Metadata can be provided in Pandoc markdown format with metadata blocks
       <http://pandoc.org/MANUAL.html#metadata-blocks> at the top of a markdown file or in YAML
       format like this:

         ---
         title: a title
         author:
           - first author
           - second author
         published: true
         ...

       Pandoc supports document metadata build of strings ("MetaString"), boolean values
       ("MetaBool"), lists ("MetaList"), key-value maps ("MetaMap"), lists of inline elements
       ("MetaInlines") and lists of block elements ("MetaBlocks"). Simple strings and boolean
       values can also be specified via pandoc command line option "-M" or "--metadata":

         pandoc -M key=string
         pandoc -M key=false
         pandoc -M key=true
         pandoc -M key

       Perl module Pandoc::Elements exports functions to construct metadata elements in the
       internal document model and the general helper function "metadata".

METADATA ELEMENTS

       All "Meta..." elements support common element methods ("to_json", "name", ...) and return
       true for method "is_meta". Method "content" returns the blessed data structure and "value"
       returns an unblessed copy:

         $doc->meta->{author}->content->[0];   # MetaInlines
         $doc->meta->value('author')->[0];     # plain string

   value( [ $field ] )
       Called without an argument this method returns an unblessed deep copy of the metadata
       elements or "undef" if the given (sub)field does not exist.

       Can also be called with the alias "metavalue".

   MetaString
       A plain text string metadata value.

           MetaString $string
           metadata "$string"

   MetaBool
       A Boolean metadata value. The special values "false" and "FALSE" are recognized as false
       in addition to normal false values (0, "undef", "", ...).

           MetaBool $value
           metadata JSON::true()
           metadata JSON::false()

   MetaList
       A list of other metadata elements.

           MetaList [ @values ]
           metadata [ @values ]

   MetaMap
       A map of keys to other metadata elements.

           MetaMap { %map }
           metadata { %map }

   MetaInlines
       Container for a list of inlines in metadata.

           MetaInlines [ @inlines ]

   MetaBlocks
       Container for a list of blocks in metadata.

           MetaBlocks [ @blocks ]