Modal epistemic logics for many agents sometimes ignore or simplify th
e distinction between the agents themselves, and the names these agent
s use when reasoning about each other. We consider problems motivated
by practical computer science applications, and show that the simplest
theories of naming are often inadequate. The issues we raise are rela
ted to some well-known philosophical concerns, such as indexical descr
iptions, de re knowledge, and the problem of referring to nonexistent
objects. However, our emphasis is on epistemic logic as a descriptive
tool for distributed systems and artificial intelligence applications,
which leads to some nonstandard solutions. The main technical result
of this paper is a first-order modal logic, specified both axiomatical
ly and semantically (by a variant of possible-worlds semantics), that
is expressive enough to cope with all the difficulties we discuss.