typedef enum {
    URL_SCHEME_INVALID     = -1,
    URL_SCHEME_UNKNOWN     =  0,
    URL_SCHEME_FTP,
    URL_SCHEME_HTTP,
    URL_SCHEME_GOPHER,
    URL_SCHEME_MAILTO,
    URL_SCHEME_NEWS,
    URL_SCHEME_NNTP,
    URL_SCHEME_TELNET,
    URL_SCHEME_WAIS,
    URL_SCHEME_FILE,
    URL_SCHEME_MK,
    URL_SCHEME_HTTPS,
    URL_SCHEME_SHELL,
    URL_SCHEME_SNEWS,
    URL_SCHEME_LOCAL,
    URL_SCHEME_JAVASCRIPT,
    URL_SCHEME_VBSCRIPT,
    URL_SCHEME_ABOUT,
    URL_SCHEME_RES,
    URL_SCHEME_MSSHELLROOTED,
    URL_SCHEME_MSSHELLIDLIST,
    URL_SCHEME_MSHELP,
    URL_SCHEME_MAXVALUE
} URL_SCHEME;