The native-size types (native int, native unsigned int, O, and &) are a mechanism in the CLI for deferring the choice of a value’s size. These data types exist as CIL types; however, the CLI maps each to the native size for a specific processor. (For example, data type I would map to int32 on a Pentium processor, but to int64 on an IA64 processor.) So, the choice of size is deferred until JIT compilation or runtime, when the CLI has been initialized and the architecture is known. This implies that field and stack frame offsets are also not known at compile time. For languages like Visual Basic, where field offsets are not computed early anyway, this is not a hardship. In languages like C or C++, where sizes must be known when source code is compiled, a conservative assumption that they occupy 8 bytes is sometimes acceptable (for example, when laying out compile-time storage).