def blockType(self, kind):
        """Read block type switch descriptor for given kind of blockType."""
        NBLTYPES = self.verboseRead(TypeCountAlphabet(
            'BT#'+kind[0].upper(),
            description='{} block types'.format(kind),
            ))
        self.numberOfBlockTypes[kind] = NBLTYPES
        if NBLTYPES>=2:
            self.blockTypeCodes[kind] = self.readPrefixCode(
                BlockTypeAlphabet('BT'+kind[0].upper(), NBLTYPES))
            self.blockCountCodes[kind] = self.readPrefixCode(
                BlockCountAlphabet('BC'+kind[0].upper()))
            blockCount = self.verboseRead(self.blockCountCodes[kind])
        else:
            blockCount = 1<<24
        self.currentBlockCounts[kind] = blockCount
Read block type switch descriptor for given kind of blockType.