diff --git a/pframes.c b/pframes.c
index ae8c067..6ba4344 100644
--- a/pframes.c
+++ b/pframes.c
@@ -1,37 +1,97 @@
+#define _POSIX_C_SOURCE 200809L	// for strnlen
 #include <stdio.h>
 #include <string.h>
 
+char s[4] = "0000";
+char f = 'A';
+unsigned fi = 0;
+unsigned sp = 1;
+unsigned max = 0;
+unsigned sk = 1;
+unsigned mdl = 0;
+
+// recursion is fun
+int advance_sprite( int idx );
+int advance_sprite( int idx )
+{
+	if ( idx < 0 ) return 0;	// we reached the limit, bail out
+	if ( s[idx] == '9' ) s[idx] = 'A';	// from 9 to A
+	else if ( s[idx] == 'Z' )	// at limit
+	{
+		// advance the previous char
+		if ( !advance_sprite(idx-1) ) return 0;	// no more, bail out
+		s[idx] = '0';	// restart
+	}
+	else s[idx]++;	// just increment
+	return 1;
+}
+
+int advance_frame( void )
+{
+	printf("\tFrameIndex %.4s %c %d %d\n",s,f,mdl,fi);
+	fi+=sk;	// advance frame in model
+	f++;	// advance frame in sprite
+	if ( f > 'Z' )	// note that [,\ and ] are not used. this is personal preference, really
+	{
+		// we need to change the sprite name
+		if ( !advance_sprite(3) ) return 0;	// can't advance further
+		f = 'A';	// restart
+	}
+	return 1;
+}
+
 int main( int argc, char **argv )
 {
-	if ( argc < 5 ) return 1;
-	char s[4] = "TNT1";
-	char f = 'A';
-	int fi = 0;
-	int sp = 1;
-	int max = 0;
-	int sk = 1;
-	int mdl = 0;
-	strncpy(s,argv[1],4);
-	sscanf(argv[2],"%d",&fi);
-	sscanf(argv[3],"%d",&max);
-	sscanf(argv[4],"%d",&sk);
-	if ( argc > 5 ) sscanf(argv[5],"%d",&mdl);
-	if ( argc > 6 ) sscanf(argv[6],"%c",&f);
-	for ( int i=0; i<max; i+=sk )
+	if ( argc < 5 )
 	{
-		printf("\tFrameIndex %.4s %c %d %d\n",s,f,mdl,fi);
-		fi+=sk;
-		f++;
-		if ( f > 'Z' )
+		fprintf(stderr,"usage: pframes <sprite name> <start frame> <max frames> [frame step] [model index] [first sprite frame]\n"
+			"\n"
+			" - sprite name: must be 4 characters.\n"
+			" - start frame: frame offset within the model to start from.\n"
+			" - max frames: limit on frames advanced.\n"
+			" - frame step: how many frames to move each step (default:1, must be higher than zero).\n"
+			" - model index: which model to assign (default: 0).\n"
+			" - first sprite frame: which sprite frame to start from (default: A).\n"
+			"\n"
+			"   Frames advance from A to Z, wrapping around.\n"
+			"   Each wrap, the fourth char of the sprite name will be cycled, from 0 to 9, then A to Z.\n"
+			"   After ###Z is reached, the third character will by cycled instead.\n"
+			"   And so on for the second, then the first...\n"
+			"   If you somehow run out of sprite names, you need to be more reasonable. (^^;\n");
+		return 1;
+	}
+	strncpy(s,argv[1],4);
+	if ( strnlen(s,4) < 4 )
+	{
+		fprintf(stderr,"fatal: sprite name must be 4 characters.\n");
+		return 2;
+	}
+	sscanf(argv[2],"%u",&fi);
+	sscanf(argv[3],"%u",&max);
+	if ( max == 0 )
+	{
+		fprintf(stderr,"fatal: max frames must be higher than zero.\n");
+		return 4;
+	}
+	if ( argc > 4 ) sscanf(argv[4],"%u",&sk);
+	if ( sk == 0 )
+	{
+		fprintf(stderr,"fatal: frame step must be higher than zero.\n");
+		return 8;
+	}
+	if ( argc > 5 ) sscanf(argv[5],"%u",&mdl);
+	if ( argc > 6 ) sscanf(argv[6],"%c",&f);
+	if ( (f < 'A') || (f > 'Z') )
+	{
+		fprintf(stderr,"fatal: first sprite frame must be between A and Z (inclusive).\n");
+		return 16;
+	}
+	for ( unsigned i=0; i<max; i+=sk )
+	{
+		if ( !advance_frame() )
 		{
-			if ( s[3] == '9' ) s[3] = 'A';
-			else if ( s[3] == 'Z' )
-			{
-				s[2]++;
-				s[3] = '0';
-			}
-			else s[3]++;
-			f = 'A';
+			fprintf(stderr,"fatal: ran out of sprite names. please be reasonable.\n");
+			return 32;
 		}
 	}
 	return 0;
diff --git a/pframes_named.c b/pframes_named.c
new file mode 100644
index 0000000..0921b44
--- /dev/null
+++ b/pframes_named.c
@@ -0,0 +1,99 @@
+#define _POSIX_C_SOURCE 200809L	// for strnlen
+#include <stdio.h>
+#include <string.h>
+
+char s[4] = "0000";
+char f = 'A';
+unsigned fi = 0;
+unsigned sp = 1;
+unsigned max = 0;
+unsigned sk = 1;
+unsigned mdl = 0;
+char *anm = NULL;
+
+// recursion is fun
+int advance_sprite( int idx );
+int advance_sprite( int idx )
+{
+	if ( idx < 0 ) return 0;	// we reached the limit, bail out
+	if ( s[idx] == '9' ) s[idx] = 'A';	// from 9 to A
+	else if ( s[idx] == 'Z' )	// at limit
+	{
+		// advance the previous char
+		if ( !advance_sprite(idx-1) ) return 0;	// no more, bail out
+		s[idx] = '0';	// restart
+	}
+	else s[idx]++;	// just increment
+	return 1;
+}
+
+int advance_frame( void )
+{
+	printf("\tFrame %.4s %c %d \"%s:%d\"\n",s,f,mdl,anm,fi);
+	fi+=sk;	// advance frame in model
+	f++;	// advance frame in sprite
+	if ( f > 'Z' )	// note that [,\ and ] are not used. this is personal preference, really
+	{
+		// we need to change the sprite name
+		if ( !advance_sprite(3) ) return 0;	// can't advance further
+		f = 'A';	// restart
+	}
+	return 1;
+}
+
+int main( int argc, char **argv )
+{
+	if ( argc < 4 )
+	{
+		fprintf(stderr,"usage: pframes-named <sprite name> <anim name> <max frames> [frame step] [model index] [first sprite frame]\n"
+			"\n"
+			" - sprite name: must be 4 characters.\n"
+			" - anim name: name of the animation to use.\n"
+			" - max frames: limit on frames advanced.\n"
+			" - frame step: how many frames to move each step (default: 1, must be higher than zero).\n"
+			" - model index: which model to assign (default: 0).\n"
+			" - first sprite frame: which sprite frame to start from (default: A).\n"
+			"\n"
+			"   Frames advance from A to Z, wrapping around.\n"
+			"   Each wrap, the fourth char of the sprite name will be cycled, from 0 to 9, then A to Z.\n"
+			"   After ###Z is reached, the third character will by cycled instead.\n"
+			"   And so on for the second, then the first...\n"
+			"   If you somehow run out of sprite names, you need to be more reasonable. (^^;\n");
+		return 1;
+	}
+	strncpy(s,argv[1],4);
+	if ( strnlen(s,4) < 4 )
+	{
+		fprintf(stderr,"fatal: sprite name must be 4 characters.\n");
+		return 2;
+	}
+	anm = argv[2];	// can be used directly, but this makes the code more readable
+	sscanf(argv[3],"%u",&max);
+	if ( max == 0 )
+	{
+		fprintf(stderr,"fatal: max frames must be higher than zero.\n");
+		return 4;
+	}
+	if ( argc > 4 ) sscanf(argv[4],"%u",&sk);
+	if ( sk == 0 )
+	{
+		fprintf(stderr,"fatal: frame step must be higher than zero.\n");
+		return 8;
+	}
+	if ( argc > 5 ) sscanf(argv[5],"%u",&mdl);
+	if ( argc > 6 ) sscanf(argv[6],"%c",&f);
+	if ( (f < 'A') || (f > 'Z') )
+	{
+		fprintf(stderr,"fatal: first sprite frame must be between A and Z (inclusive).\n");
+		return 16;
+	}
+	for ( unsigned i=0; i<max; i+=sk )
+	{
+		if ( !advance_frame() )
+		{
+			fprintf(stderr,"fatal: ran out of sprite names. please be reasonable.\n");
+			return 32;
+		}
+	}
+	return 0;
+}