xml - Why does DTD validation fail when optional child element is omitted? -

the xml document has embedded dtd declaration , fails.

here dtd:

<!doctype movielist [  <!element movielist (movie+)> <!element movie (title+, rating+, runtime+, genrelist*, datereleased+,            country+, review+, description+, director+)>  <!element title (#pcdata)> <!element rating (#pcdata)> <!element runtime (#pcdata)> <!element genrelist (genre+)> <!element genre (#pcdata)> <!element datereleased (#pcdata)> <!element country (#pcdata)> <!element review (#pcdata)> <!element description (#pcdata)> <!element director (#pcdata)> ]> 

and here xml elements:

<movielist> <movie>     <title>jaws</title>     <rating>pg</rating>     <runtime>124 minutes</runtime>     <genrelist>         <genre>adventure</genre>         <genre>thriller</genre>     </genrelist>     <datereleased>20 june 1975</datereleased>     <country>usa</country>     <review>8</review>     <description>when gigantic great white shark begins menace      small island community of amity, police chief, marine      scientist , grizzled fisherman set out stop it.</description>     <director>steven spielberg</director> </movie>  <movie>     <title>the good, bad , ugly</title>     <rating>nr</rating>     <runtime>161 minutes</runtime>         <genre>western</genre>     <datereleased>23 december 1966</datereleased>     <country>italy</country>     <review>9</review>     <description>a bounty hunting scam joins 2 men in uneasy      alliance against third in race find fortune in gold buried      in remote cemetery.</description>     <director>sergio leone</director> </movie> </movielist> 

it fails have 1 genre , not wrapped elements genrelist. should work because in movie element declaration have genrelist* means, genrelist appear 0 or more.

you explain results , expectations well.

you're right genrelist* means genrelist may absent. however, if genrelist absent, children cannot present. content model movie has no provision genre without genrelist, xml invalid per dtd, reported correctly.