a

access control list: X maintains a list of hosts from which client programs can be run. By default, only programs on the local host can use the display, plus any hosts specified in an initial list read by the server. This access control list can be changed by clients on the local host. Some server implementations can also implement other authorization mechanisms in addition to or in place of this mechanism. The action of this mechanism can be conditional based on the authorization protocol name and data received by the server at connection setup.
action: A function that is designed to handle an input event. CLUE input processing consists of matching an event with an event specification found in a contact's event-translations slot and then calling actions associated with the matching event specification.
active grab: A grab is active when the pointer or keyboard is actually owned by the single grabbing client.
ancestors: If W is an inferior of A, then A is an ancestor of W.
atom: A unique ID corresponding to a string name. Atoms are used to identify properties, types, and selections.