NAME
        GetTagData -- obtain the data corresponding to a tag. (V36)

   SYNOPSIS
        value = GetTagData(tagValue,defaultVal,tagList);
        D0                 D0       D1         A0

        ULONG GetTagData(Tag,ULONG,struct tagitem *);

   FUNCTION
        Searches a tag list for a matching tag, and returns the
        corresponding ti_Data value for the tagitem found. if no match is
        found, this function returns the value passed in as 'default'.

   INPUTS
        tagValue - tag value to search for.
        defaultVal - value to be returned if tagValue is not found.
        tagList - the tag list to search.

   RESULTS
        value - the ti_Data value for the first matching tagitem, or 'default'
                if a ti_Tag matching 'Tag' is not found.

   SEE ALSO
        <utility/tagitem.h>, findtagitem(), packbooltags(), nexttagitem()