diff --git a/TODO.md b/TODO.md
new file mode 100644
index 0000000..60a61fc
--- /dev/null
+++ b/TODO.md
@@ -0,0 +1,11 @@
+# TODO in libg1m
+## Find out what these formats are/how to parse them
+- G1L (languages for fx calculators?);
+- G1N (???);
+- G3L (languages for cg calculators);
+- G3M (like G1M?);
+
+## Correct the parsing of these formats
+- G1M (BCD, other subtypes);
+- G1A/G3A (addins for fx and cg calculators);
+- G3P (pictures).
diff --git a/include/libg1m/format.h b/include/libg1m/format.h
index 6f4ddad..8d2d56c 100644
--- a/include/libg1m/format.h
+++ b/include/libg1m/format.h
@@ -20,32 +20,7 @@
  *	In fact, there is no name for the general format, only names for the
  *	"subformats" based on this one.
  *
- *	Here's a complete list of the declinations and corresponding IDs: */
-
-enum g1m_type {
-	/* fx-CG add-in */
-	g1m_typ_addin_cg = 0x2c,
-
-	/* mcs (main memory) save */
-	g1m_typ_mcs = 0x31,
-
-	/* e-activity (document) */
-	g1m_typ_eact = 0x49,
-
-	/* g1r equivalent */
-	g1m_typ_g2r = 0x62,
-
-	/* g3m (fx-CG program) */
-	g1m_typ_g3m = 0x75,
-
-	/* g3p (fx-CG picture) */
-	g1m_typ_g3p = 0x7d,
-
-	/* add-in (compiled program) */
-	g1m_typ_addin = 0xf3,
-};
-
-/*	It all starts with a header, called Standard Header by Simon Lothar.
+ *	It all starts with a header, called Standard Header by Simon Lothar.
  *	This Standard Header contains the total filesize, the G1M type (add-in,
  *	MCS, e-acts), some data that will be useful for the MCS type, and some
  *	magic and control bytes.
@@ -57,7 +32,7 @@ enum g1m_type {
  *	it can simply be obtained bitwise-AND-ing with 0xff. */
 
 struct standard_header {
-	/* the file identifier, should be "USBPower". */
+	/* the file identifier - see below */
 	uint8_t main_id[8];
 
 	/* our filetype! */
@@ -90,6 +65,52 @@ struct standard_header {
 	uint16_t number;
 };
 
+/*	At the beginning, we thought "USBPower" was some magic sequence we would
+ *	systematically find in the "main_id" field. But a counter example came:
+ *	the G3L, where the main ID was "Ly755   ".
+ *
+ *	So here are the known main IDs: */
+
+enum g1m_main_id {
+	/* "USBPower": the most common one */
+	g1m_mid_usbpower,
+
+	/* "Ly755   ": fx-CG specific types */
+	g1m_mid_ly755,
+};
+
+/*	Here are USBPower types: */
+
+enum g1m_usbpower_type {
+	/* fx-CG add-in */
+	g1m_usbpower_type_addin_cg = 0x2c,
+
+	/* mcs (main memory) save */
+	g1m_usbpower_type_mcs = 0x31,
+
+	/* e-activity (document) */
+	g1m_usbpower_type_eact = 0x49,
+
+	/* g1r equivalent */
+	g1m_usbpower_type_g2r = 0x62,
+
+	/* g3m (fx-CG program) */
+	g1m_usbpower_type_g3m = 0x75,
+
+	/* g3p (fx-CG picture) */
+	g1m_usbpower_type_g3p = 0x7d,
+
+	/* add-in (compiled program) */
+	g1m_usbpower_type_addin = 0xf3,
+};
+
+/*	And here are Ly755 types: */
+
+enum g1m_ly755_type {
+	/* language file */
+	g1m_ly755_type_lang = 0x2c
+};
+
 # pragma pack()
 
 /*	After the Standard Header is read and the G1M type is read, we have parts,
diff --git a/include/libg1m/internals/log.h b/include/libg1m/internals/log.h
index ec7a28f..edb25aa 100644
--- a/include/libg1m/internals/log.h
+++ b/include/libg1m/internals/log.h
@@ -55,7 +55,7 @@
 
 /* Functions prototypes */
 void g1m_log_mem(const char *prefix, void *m, size_t n);
-const char *g1m_get_type_string(int code);
+const char *g1m_get_type_string(int main_id, int type);
 const char *g1m_get_mcs_ftype_string(int code);
 const char *g1m_get_eact_ltype_string(int code);
 
diff --git a/src/core/log.c b/src/core/log.c
index 21c623c..6526f73 100644
--- a/src/core/log.c
+++ b/src/core/log.c
@@ -135,17 +135,25 @@ void g1m_log_mem(const char *prefx, void *m, size_t n)
  *	@return				the string.
  */
 
-const char *g1m_get_type_string(int code)
+const char *g1m_get_type_string(int main_id, int type)
 {
-	switch (code) {
-		case g1m_typ_addin_cg: return ("fx-CG addin");
-		case g1m_typ_mcs: return ("mcs");
-		case g1m_typ_eact: return ("e-activity");
-		case g1m_typ_g2r: return ("mcs (g2r)");
-		case g1m_typ_g3p: return ("g3p");
-		case g1m_typ_addin: return ("addin");
-		default: return ("unknown");
+	switch (main_id) {
+	case g1m_mid_usbpower:
+		switch (type) {
+			case g1m_usbpower_type_addin_cg: return ("fx-CG addin");
+			case g1m_usbpower_type_mcs: return ("mcs");
+			case g1m_usbpower_type_eact: return ("e-activity");
+			case g1m_usbpower_type_g2r: return ("mcs (g2r)");
+			case g1m_usbpower_type_g3p: return ("g3p");
+			case g1m_usbpower_type_addin: return ("addin");
+		}
+		break;
+	case g1m_mid_ly755:
+		switch (type) {
+			case g1m_ly755_type_lang: return ("fx-CG language file");
+		}
 	}
+	return ("unknown");
 }
 
 /**
diff --git a/src/parse/main.c b/src/parse/main.c
index 04d4ff6..966dda3 100644
--- a/src/parse/main.c
+++ b/src/parse/main.c
@@ -9,6 +9,23 @@
 /* ************************************************************************** */
 #include <libg1m/internals.h>
 
+/**
+ *	get_main_id:
+ *	Get numerical main ID based on the main ID string.
+ *
+ *	@arg	s			the 8-bytes buffer containing the ID.
+ *	@return				the main ID or -1 if the main ID is unknown.
+ */
+
+static int get_main_id(unsigned char *s)
+{
+	if (!memcmp(s, "USBPower", 8))
+		return (g1m_mid_usbpower);
+	if (!memcmp(s, "Ly755   ", 8))
+		return (g1m_mid_ly755);
+	return (-1);
+}
+
 /**
  *	g1m_parse:
  *	Parse a G1M file.
@@ -50,37 +67,56 @@ int g1m_parse(g1m_t *handle, FILE *stream)
 		return (g1m_error_magic);
 	}
 
+	/* get the main ID */
+	int main_id = get_main_id(hd.main_id);
+	if (main_id < 0) {
+		log_fatal("Main ID is unknown: '%.8s'", hd.main_id);
+		return (g1m_error_magic);
+	}
+
 	/* log some data */
 	log_info("Standard Header Main ID is '%.8s'", hd.main_id);
 	log_info("Standard Header Type is '%s' (0x%02x)",
-		g1m_get_type_string(hd.type), hd.type);
+		g1m_get_type_string(main_id, hd.type), hd.type);
 	log_info("Standard Header filesize is %uo", hd.filesize);
 	log_info("Standard Header num is %d.", hd.number);
 
 	/* subparse. */
 	handle->is_cg = 0;
-	switch (hd.type) {
-		case g1m_typ_addin:
+	switch (main_id) {
+	case g1m_mid_usbpower:
+		switch (hd.type) {
+		case g1m_usbpower_type_addin:
 			handle->type = g1m_type_addin;
 			return (g1m_parse_addin(handle, stream));
-		case g1m_typ_addin_cg:
+		case g1m_usbpower_type_addin_cg:
 			handle->type = g1m_type_addin;
 			handle->is_cg = 1;
 			return (g1m_parse_addin_cg(handle, stream, &hd));
-		case g1m_typ_g2r:
-		case g1m_typ_mcs:
+		case g1m_usbpower_type_g2r:
+		case g1m_usbpower_type_mcs:
 			handle->type = g1m_type_mcs;
 			return (g1m_parse_mcs(handle, stream, hd.number));
-		case g1m_typ_eact:
+		case g1m_usbpower_type_eact:
 			handle->type = g1m_type_eact;
 			return (g1m_parse_eact(handle, stream));
-		case g1m_typ_g3p:
+		case g1m_usbpower_type_g3p:
 			handle->type = g1m_type_pict;
 			handle->is_cg = 1;
 			return (g1m_parse_g3p(handle, stream, &hd));
 		default:
 			log_info("Type not managed (yet?): 0x%02x", hd.type);
+		}
+		break;
+	case g1m_mid_ly755:
+		switch (hd.type) {
+		case g1m_ly755_type_lang:
+			log_info("Lang type isn't managed yet.");
 			break;
+		default:
+			log_info("Type not managed (yet?): 0x%02x", hd.type);
+		}
+		break;
 	}
 
 	/* no error */