SpySpeak for anything that is within a monitorable environment, usually people or objects, such as subjects or objectives (e.g. ordinance, documents, contraband, etc.) being observed. If one is tailing (following) said subject/objective and has the subject/objective within visual range, is considered "in pocket." A target/objective that is "out of pocket" is one that is not monitorable.
Simply put, "in pocket" means you can see your mark and know what your mark is doing, hence making your actions as the observer smarter and safer; "out of pocket" is the opposite, creating a potentially uncontrolled environment which is always a liability.
"Target exiting structure, in pocket walking south on Michigan Avenue. Target has entered a taxi, headed west on Lawrence Avenue, out of pocket."
"Subjects are taking the ordinance off the plane; ordinance is in pocket in a black SUV, parked; primary target is out of pocket, presumably inside the plane. Awaiting visual confirmation of target."