Type system categorization

Item	Scope	Description	Impact
atomic_cell	static	Structure of an atomic cell: timestamp, live/dead, tombstone, deletion time, value	Generating accessors for fields
atomic_cell instance	runtime	Which variant of an atomic_cell is engaged for a particular value?	Storage compression
underlying type	schema	Comparators, arithmetic, fixed vs. variable size	Accessors, comparators, arithmetic, whether an "empty bit" is needed
collection vs. atomic	schema	whether to use atomic_cell or something else	Accessors
static rows, clustering keys	schema	Whether they exist or not	run-time or llvm-time optional<>
number of columns in row	schema	How many columns were defined in the schema	pre-determination of storage formats
number of cells in row	runtime	How many cells are actually present	selection of sparse vs. dense storage format
partition key, clustering key types	schema	What types make up a partition key or clustering key	Generation of comparators, hashers
value	runtime	Actual value in cell	Whether we can use the small-string optimization or not, indirection
collection	schema	Types of cells in collection, type of collection	Generation of accessors
cell count in collection	runtime	Actual cell count in a mutation	Whether to use linear or treelike storage