Ethernet hardware addresses are 48 bits, expressed as 12 hexadecimal digits (0-9, plus A-F, capitalized). These 12 hex digits consist of the first/left 6 digits (which should match the vendor of the Ethernet interface within the station) and the last/right 6 digits which specify the interface serial number for that interface vendor. MAC address need to be 12 length of string that from 0123456789 and ABCDEF , any value other than those will be invalid to Operation System.
Ethernet addresses might be written unhyphenated (e.g. 123456789ABC), or with one hyphen (e.g. 123456-789ABC), but should be written hyphenated by octets (e.g. 12-34-56-78-9A-BC). These addresses are physical station addresses, not multicast nor broadcast, so the second hex digit (reading from the left) will be even, not odd.
Good Example: [00:50:56:C0:00:08]
Bad Example: [00:50:56:C0:00:0X]