M2. An implementation shall specify which interval formats it supports (it is permitted to support only one). Support consists of the following two items.
- For each supported interval format, operations (as P1788 will in due course specify) shall be provided, to at least SRSF level - see R6.6.
- Conversions shall be provided between any two supported interval formats - see R6.5.
To make the text coherent, I think that you must change "it is permitted to support only one" to "it must support at least one".
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Hossam Fahmy
Assistant Professor
Electronics and Communications Department
Cairo University
Egypt