How are installation sizes of ball bearings standardised?

Many rolling bearings are available as sealed version. The sealing takes place according to the principle of the shaft seal. The following manufacturer-specific seal designations are possible:

• Z = one-sided sheet metal cover disc with gap seal
• ZZ/2Z = as above, from both sides
• RS = one-sided, grinding rubber seal
• LB = as above
• 2RS = as above, from both sides
• LLU = as above, non-contact rubber seal, from both sides
• EE = as above, touching from both sides, grinding
• RZ = one-sided, non-contact rubber seal
• LB = as above
• 2RZ = as above, from both sides
• LLB = as above