The term query has multiple meanings in the PSYC context. That's why we try to avoid the use of it, and replace the term with specific vocabulary.

Dialog mode

In the tradition of BITNET and IRC the /query command has been in charge of managing one-to-one conversations. We prefer the /talk command and try to use the term dialog for this.

Query / Retrieval

The XMPP frequently employs a pull/discovery rather than a push data model using its Information & Query stanza type <iq/>. You may occasionally hear of query in this context.

PSYC tries to use a push approach over the Query/Retrieval model and tries to unify all asynchronous update requirements (like when your client was offline or you just installed a new one) using a generalized state synchronization approach, rather than isolated back and forth protocols.

The "?" operator

In the PSYC routing layer the ? operator is supposed to stand for something also known as _query. It requests variables from the other side. It is however not ensured, that the existence is justified.

In the old linking process we also have a special case of a _query_password method in use.

Databases

The term is obviously also used in the SQL context, but that hardly has something to do with PSYC, indeed.