It refers to the lowest level code of the item used in B/M. The level code for not only one product but also all products is considered. As shown in the figure, for example, the low level code of Part b used at Level 1 and Level 2 is 2 in Product Z. The low level code set in this way is registered to each item, and is used to perform a level-by-level explosion.
In computer science, a low-level programming language is a programming language that provides little or no abstraction from a computer's instruction set architecture. Generally this refers to either machine code or assembly language. The word "low" refers to the small or nonexistent amount of abstraction between the language and machine language; because of this, low-level languages are sometimes described as being "close to the hardware".
Machine code is the only language a microprocessor can process directly without a previous transformation. Currently, programmers almost never write programs directly in machine code, because it requires attention to numerous details which a high-level language would handle automatically, and also requires memorizing or looking up numerical codes for every instruction that is used. For this reason, second generation programming languages provide one abstraction level on top of the machine code. Even in the early days of coding on computers like the TX-0 and PDP-1, the first thing that the MIT hackers did was write assemblers
Assembly language has no semantics and no specification, being only a mapping of human-readable symbols, including symbolic addresses, to opcodes, addresses, numeric constants, strings and so on. Typically, one machine instruction is represented as one line of assembly code. Assemblers produce object files which may be linked with other object files or loaded on their own.
Most assemblers provide macros.