This section contains the layout of the data structures used to describe a CIL method and its exceptions. Method bodies can be stored in any read-only section of a PE file. The MethodDef (§II.22.26) records in metadata carry each method's RVA.
A method consists of a method header immediately followed by the method body, possibly followed by extra method data sections (§II.25.4.5), typically exception handling data. If exception-handling data is present, then CorILMethod_MoreSects flag (§II.25.4.4) shall be specified in the method header and for each chained item after that.
There are two flavors of method headers – tiny (§II.25.4.2) and fat (§II.25.4.3). The two least significant bits in a method header indicate which type is present (§II.25.4.1). The tiny header is 1 byte long and stores only the method's code size. A method is given a tiny header if it has no local variables, maxstack is 8 or less, the method has no exceptions, the method size is less than 64 bytes, and the method has no flags above 0x7. Fat headers carry full information – local vars signature token, maxstack, code size, flag. Tiny method headers can start on any byte boundary. Fat method headers shall start on a 4-byte boundary.