-//First byte is 26
-#define ISO15693_INVENTORY 0x01
-#define ISO15693_STAYQUIET 0x02
-//First byte is 02
-#define ISO15693_READBLOCK 0x20
-#define ISO15693_WRITEBLOCK 0x21
-#define ISO15693_LOCKBLOCK 0x22
-#define ISO15693_READ_MULTI_BLOCK 0x23
-#define ISO15693_SELECT 0x25
-#define ISO15693_RESET_TO_READY 0x26
-#define ISO15693_WRITE_AFI 0x27
-#define ISO15693_LOCK_AFI 0x28
-#define ISO15693_WRITE_DSFID 0x29
-#define ISO15693_LOCK_DSFID 0x2A
-#define ISO15693_GET_SYSTEM_INFO 0x2B
-#define ISO15693_READ_MULTI_SECSTATUS 0x2C
+// ISO15693 COMMANDS
+#define ISO15693_INVENTORY 0x01
+#define ISO15693_STAYQUIET 0x02
+#define ISO15693_READBLOCK 0x20
+#define ISO15693_WRITEBLOCK 0x21
+#define ISO15693_LOCKBLOCK 0x22
+#define ISO15693_READ_MULTI_BLOCK 0x23
+#define ISO15693_SELECT 0x25
+#define ISO15693_RESET_TO_READY 0x26
+#define ISO15693_WRITE_AFI 0x27
+#define ISO15693_LOCK_AFI 0x28
+#define ISO15693_WRITE_DSFID 0x29
+#define ISO15693_LOCK_DSFID 0x2A
+#define ISO15693_GET_SYSTEM_INFO 0x2B
+#define ISO15693_READ_MULTI_SECSTATUS 0x2C
+
+// ISO15693 REQUEST FLAGS
+#define ISO15693_REQ_SUBCARRIER_TWO (1<<0)
+#define ISO15693_REQ_DATARATE_HIGH (1<<1)
+#define ISO15693_REQ_INVENTORY (1<<2)
+#define ISO15693_REQ_PROTOCOL_EXT (1<<3) // RFU
+#define ISO15693_REQ_OPTION (1<<6) // Command specific option selector
+// when REQ_INVENTORY is not set
+#define ISO15693_REQ_SELECT (1<<4) // only selected cards response
+#define ISO15693_REQ_ADDRESS (1<<5) // this req contains an address
+// when REQ_INVENTORY is set
+#define ISO15693_REQINV_AFI (1<<4) // AFI Field is present
+#define ISO15693_REQINV_SLOT1 (1<<5) // 1 Slot (16 slots if not set)
+
+// ISO15693 RESPONSE FLAGS
+#define ISO15693_RES_ERROR (1<<0)
+#define ISO15693_RES_EXT (1<<3) // Protocol Extention
+
+// ISO15693 RESPONSE ERROR CODES
+#define ISO15693_NOERROR 0x00
+#define ISO15693_ERROR_CMD_NOT_SUP 0x01 // Command not supported
+#define ISO15693_ERROR_CMD_NOT_REC 0x02 // Command not recognized (eg. parameter error)
+#define ISO15693_ERROR_CMD_OPTION 0x03 // Command option not supported
+#define ISO15693_ERROR_GENERIC 0x0F // No additional Info about this error
+#define ISO15693_ERROR_BLOCK_UNAVAILABLE 0x10
+#define ISO15693_ERROR_BLOCK_LOCKED_ALREADY 0x11 // cannot lock again
+#define ISO15693_ERROR_BLOCK_LOCKED 0x12 // cannot be changed
+#define ISO15693_ERROR_BLOCK_WRITE 0x13 // Writing was unsuccessful
+#define ISO15693_ERROR_BLOCL_WRITELOCK 0x14 // Locking was unsuccessful