The spec says:

"Uses Crockford's base32 for better efficiency and readability (5 bits per character)"

"Crockford's Base32 is used as shown. This alphabet excludes the letters I, L, O, and U to avoid confusion and abuse."

However it is not exactly clear does this mean only using the character set 0123456789ABCDEFGHJKMNPQRSTVWXYZ or does it mean using also the Crockford base32 features such as treating i and l as 1, treating o as 0 and ignoring hyphens in the string?