I have reviewed this document as part of the ARTART review team. Verdict: Almost ready There are a few things that need better definitions to be comprehensible enough for interoperable implementation. There is also one confusing formatting error that should be fixed before publication. Weak definitions: - "Maintenance event" is never defined. From context, it is possible to infer that a maintenance event refers to some service being partially or wholly unavailable in the time interval given; given that this is the whole point of the document, this should be explicit. It should also be explicit that the service will be either fully and correctly available or not available at all, and that no harm (apart from being denied service) will come from trying to access the service in the maintenance interval; "maintenance" that, for instance, puts a test database up where the normal database is would be just a broken service, not "maintenance" in this sense. (If broken stuff might happen, I think you need a new impact value in addition to "full", "partial" or "none" - something like "STAYAWAYYOUWILLREGRETEVENTHINKINGABOUTTRYING"). - "maint:connection" and "maint:implementation" make very little sense as described. They may refer to having to reconnect the EPP service or to upgrade the EPP schema in use, but since the "maint:name" element of "maint:system" seems to encompass WHOIS and others, the actions that may be required are not clear; an instruction to "do something connection-related" cannot be interoperably implemented. Suggestion: Either delete these elements or (if intended to be consumed by a human) add the option to add a text description of what should be done. - pollType seems somewhat strange. The implicit definition seems to be that the client polls the server and the server replies with a list of outstanding maintenance events, with the value "create" returned the first time the server tells the client about the event. This implies that the server is required to keep state of what it has told each client about the event; same goes for event deletion. If such a state tracking requirement is indeed intended, this should be explicit. Formatting issues: In the list of elements in section 3, the indentation of and the succeeding elements indicates that it is an element of . Examples indicate that it is an element of , which makes a lot more sense. Precision in definition issues: The incantation "The extended date-time form using upper case "T" and "Z" characters defined in ISO 8601 [RFC3339] MUST be used to represent date-time values." is not precise (I don't know if it's common) - it seems to claim that RFC 3339 is ISO 8601, which is just confusing. Suggested format: "The date-time format defined as "date-time" in [RFC3339], with time-offset="Z", MUST be used". Styllistic issues: The cuteness of using "upDate" as both meaing "update" and "this is a date" hurts the eyes :-) Unless there is tradition for this name, I'd suggest being boring and using "updateDate". Having migration considerations before item descriptions looks a bit weird when reading the document top to bottom. Would it be nicer to move it after section 4? I have not attempted to verify the schema, nor have I attempted to check the document against common styles for EPP extensions. If comments touch on things that are mandated by common EPP practices, feel free to consider these comments overridden. Hope this is helpful.