enforsed compilation with -W -Werror

diff --git a/skeletons/BMPString.c b/skeletons/BMPString.c
index 596974e..93584c8 100644
--- a/skeletons/BMPString.c
+++ b/skeletons/BMPString.c
@@ -23,6 +23,7 @@
 	  / sizeof(asn1_DEF_BMPString_tags[0]),
 	1,	/* Single UNIVERSAL tag may be implicitly overriden */
 	-1,	/* Both ways are fine */
+	0	/* No specifics */
 };
 
 /*
@@ -37,6 +38,9 @@
 	char scratch[128];			/* Scratchpad buffer */
 	char *p;
 
+	(void)td;	/* Unused argument */
+	(void)ilevel;	/* Unused argument */
+
 	if(!st || !st->buf) return cb("<absent>", 8, app_key);
 
 	wchar = (uint16_t *)st->buf;