GN_Xnx, Index next entry in linked list

Register parameters

RST 20H, DEFW $4409
IN:
     CDE = pointer to previous entry
     BHL = pointer to current entry

OUT, if call successful:
     Fc = 0
     CDE = pointer to old current entry (ie. BHL(in))
     BHL = pointer to next entry
     Fz = 1, if BHL(out) = 0.

OUT, if call failed:
     Fc = 1
          If BHL(in) = 0; BHL(in) and CDE(in) are then preserved.
     A = error code:
          RC_EOF ($09), attempt to step beyond start or end of list

Registers changed after return:
     ......../IXIY same
     AFBCDEHL/.... different 

Notes

For more details, read Linked lists.

Related calls

GN_Xdl, delete an entry from a linked list 
GN_Xin, insert an entry into a linked list