You may want to retrieve the list of topics of a sub category. here are the required parameters
user : Pseudo of a forum administrator
pwd : Password of a forum administrator
idforum : ID of the forum where the sub category is located
idcat : ID of the category where the sub category is located
idsubcat : ID of the sub category that we want to retrieve
limit : maximum number of topic titles that the webservice should fetch
A PHP example
The webservice will return a parameter and a XML feed
nbtopics : returns the number of topics of the sub category
topiclist : XML feed :