In Siemens automation, "MLFB number" is a German acronym forMaschinelles Lesbares Fabrikatebezeichnung, which translates to English  "Machine-Readable Product Designation".

Essentially, the MLFB number is the unique part number or catalog number used by Siemens to identify a specific product or component.

Key Details

• Purpose: The MLFB number uniquely identifies a specific product, including its series, type, features, and version. This is crucial for ordering the correct part, technical support, documentation, and spare parts management.
• Structure: It is typically a long alphanumeric string (e.g., 6ES7331-1KF01-0AB1) that follows a specific, standardized structure, with certain positions indicating different product characteristics.
• Usage: You can find the MLFB number on the device's nameplate.
• German Origin: As requested, yes, the term is German and widely used within the global Siemens organization.
• Character Restriction: The letters "I" and "O" are intentionally not used in the MLFB to avoid confusion with the digits "1" and "0".

Forum members can use  "MLFB number" when your post your question, that will help expert to quick identify your products , getting system information and easier to target your problem.

here is an example MLFB using in the documentation, which is SIMODRIVE 611A spindle control , 

i attached a page , and highlight the MLFB locations