PPP implemntation

I’m currently working with the NET+WORKS 6.0 on the NS7520 Developement Board using the GH MULTI2000 Development Environement . in the file named naPPP.h i found this : [b][b]import int ppp_init(netdev * ndp); import int ppp_updown(netdev * ndp, u16 flags, char * options); import st ppp_scomm(m * mp); import int ppp_linkup( char *devname ); import int ppp_linkdown( char *devname ); import void ppp_transmit_complete( netdev *ndp ); import int ppp_start (m *mp); Do somebody know what this “import” means or does (same for this “st”). Can somebody tell me where i can find a description or the code of those functions because i cannot find it in the API neither in the furnished C files. thanks.