AcceptShift is the right-shift count for the first byte info byte to get the index into the AcceptRanges table.

ASCII identifies a UTF-8 byte as ASCII.

FirstInvalid indicates a byte is invalid as a first byte of a UTF-8 sequence.

1011 1111.

1000 0000.

SizeMask is a mask for the size bits.

AcceptRanges is a slice of AcceptRange values.

First is information about the first byte in a UTF-8 sequence.

AcceptRange gives the range of valid values for the second byte in a UTF-8 sequence for any value for First that is not ASCII or FirstInvalid.