A registration authority or maintenance agency is a body given the responsibility of maintaining lists of codes under international standards and issuing new codes to those wishing to register them.

ISO standards having registration authorities are:

• ISO 4
• ISO 639
• ISO 2108
• ISO 2375, which governs registrations for ISO 646 and ISO 2022
• ISO 3166
• ISO 3297
• ISO 3779
• ISO 3780
• ISO 3901
• ISO 4100
• ISO 4217
• ISO 4343
• ISO 6166
• ISO 6346
• ISO 6523
• ISO 7350 (see also ISO 10367 )
• ISO 7372
• ISO 7812
• ISO 7816
• ISO 7942
• ISO 8583
• ISO 8632
• ISO 8651
• ISO 8802
• ISO 8805
• ISO 8806
• ISO 8824
• ISO 9070
• ISO 9141
• ISO 9281
• ISO 9362
• ISO 9592
• ISO 9593
• ISO 9636
• ISO 9834
• ISO 9897
• ISO 9973
• ISO 9979
• ISO 10036
• ISO 10160
• ISO 10161
• ISO 10383
• ISO 10444
• ISO 10486
• ISO 10641
• ISO 10957
• ISO 10962
• ISO 11076
• ISO 11576
• ISO 13499
• ISO 13522
• ISO 13764
• ISO 13800
• ISO 13818
• ISO 14496
• ISO 15022
• ISO 15292
• ISO 15511
• ISO 15706
• ISO 15707
• ISO 15897
• ISO 15924
• ISO 18245
• ISO 21000
• ISO 23950