indicates a hexadecimal or ASCII formatted WEP key. Hex keys are either 10 or 26 hexadecimal characters (ie "5f782f2f5f" or "732f2d712e4a394a375d366931"), while ASCII keys are either 5 or 13 ASCII characters (ie "abcde" or "blahblah99$*1").
indicates a WEP passphrase (ex "I bought a duck on my way back from the market 235Q&^%^*%") instead of a hexadecimal or ASCII key. Passphrases are between 8 and 64 characters inclusive and are hashed the actual WEP key using the MD5 hash algorithm.
unknown WEP key type
The #NMWepKeyType values specify how any WEP keys present in the setting are interpreted. There are no standards governing how to hash the various WEP key/passphrase formats into the actual WEP key. Unfortunately some WEP keys can be interpreted in multiple ways, requiring the setting to specify how to interpret the any WEP keys. For example, the key "732f2d712e4a394a375d366931" is both a valid Hexadecimal WEP key and a WEP passphrase. Further, many ASCII keys are also valid WEP passphrases, but since passphrases and ASCII keys are hashed differently to determine the actual WEP key the type must be specified.