Index: layer_grp.h
===================================================================
--- layer_grp.h	(revision 19182)
+++ layer_grp.h	(revision 19183)
@@ -103,6 +103,7 @@
 /* Same as pcb_layer_list but lists layer groups. A group is matching
    if any layer in that group matches mask. */
 int pcb_layergrp_list(pcb_board_t *pcb, pcb_layer_type_t mask, pcb_layergrp_id_t *res, int res_len);
+int pcb_layergrp_listp(pcb_board_t *pcb, pcb_layer_type_t mask, pcb_layergrp_id_t *res, int res_len, int purpi, const char *purpose);
 int pcb_layergrp_list_any(pcb_board_t *pcb, pcb_layer_type_t mask, pcb_layergrp_id_t *res, int res_len);
 
 /* Put a layer in a group (the layer should not be in any other group);