A type as the wire describes it (MS-TDS 2.2.5.4 TYPE_INFO): the token's type byte with its length, precision and scale, or collation, as the server sends it in COLMETADATA and a client sends it for a parameter. The wire has fewer types than T-SQL (int arrives as TIIntN 4 or TIInt4; json and vector as character types): Hmssql.SqlType names the declared type. RawParam takes one to send a value with a wire type of your choosing.

The schema collection of a typed xml column or parameter.

MS-TDS 2.2.5.5.2 UDT_INFO, as the server sends it in COLMETADATA and RETURNVALUE.

Sentinel length for varchar(max), nvarchar(max), varbinary(max).

An undecoded column or parameter value; Nothing is SQL NULL.

Precision and scale of decimal / numeric, which must satisfy 1 <= precision <= 38 and scale <= precision (MS-TDS 2.2.5.5.1.3).

A column's or parameter's TYPE_INFO, as COLMETADATA and RETURNVALUE carry it.

TYPE_INFO as a Put: writeTypeInfo.

Write a value as it appears in RPC parameters. Fails (with error) if valueProblem finds invalid framing, including a non-NULL empty payload whose length would encode NULL. This does not validate the type declaration or the payload's semantic value.

putValue without the check, for a value checked with valueProblem. Invalid lengths can wrap or encode NULL (writeValue).

How a type's values are delimited on the wire (lengthKind).

How values of the type are delimited.

Why a value can't be sent as a parameter of this type, if it can't: a lengthProblem, or an empty value of a type whose length prefix uses 0 for NULL (every BYTE-length type, and sql_variant), which the server would read as NULL.

Why a parameter can't have this type, if it can't: a precision or scale SQL Server doesn't have (a decimal or numeric precision outside 1 through 38 or a scale above the precision, MS-TDS 2.2.5.5.1.3; a time, datetime2 or datetimeoffset scale above 7, 2.2.5.4.2), XML schema names too long for their length prefixes, or a CLR user-defined type, which hmssql doesn't send.

The T-SQL type declaration for a parameter of this type, as used in the @params argument of sp_executesql.

Whether the wire encoding of this type can carry NULL.

TYPE_INFO (MS-TDS 2.2.5.6): the type byte, then what the type carries (a length, a precision and scale, a collation, names).

A value as RPC parameters carry it, after its TYPE_INFO: nothing for a type with no value, the bytes of a fixed-length type, else a length prefix (whose NULL spelling depends on the kind, LengthKind) and the bytes, or PLP chunks. Nothing is checked here: a value too long for its length prefix wraps, and an empty BYTE-length or sql_variant payload is written as NULL. putValue checks with valueProblem first; this is for values checked already.