The table matters as much as the name
A statement that a country is a member is incomplete until it names the institution. It can also conceal a second distinction: belonging to an organization is not the same as holding a time-limited seat on one of its organs. A country list copied without its heading can therefore become misleading.
The UN Dag Hammarskjöld Library explains that the Security Council has fifteen members: five permanent and ten elected for two-year terms, with five elected each year. Its historical table attaches membership to a year and links election records. Those dates are part of the evidence, rather than optional background.
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A different organization has a different list
UNESCO maintains its own country directory, which distinguishes members, associate members and other statuses. That directory answers a UNESCO question. It should not be silently substituted for the membership of the Security Council or another body simply because both sit within the broad UN system.
An institution-specific record needs the named entity, its status, the relevant date or term and the supporting document. Preserve the organization's wording while documenting any normalization of names. A single yes-or-no field called 'UN member' cannot also answer questions about agency membership, council service or observer participation.
A presence is not a seat
A speech, meeting photograph or appearance in a document does not by itself establish membership. Begin with the appropriate roster and procedural record, then describe the specific form of participation. This editorial check is especially useful for historical research, where a present-day list may not describe the institution at the time of the event.