We present a unifying approach to multiple testing procedures for sequential
(or streaming) data by giving sufficient conditions for a sequential multiple
testing procedure to control the familywise error rate (FWER), extending to the
sequential domain the work of Goeman and Solari (2010) who accomplished this
for fixed sample size procedures. Together we call these conditions the
"rejection principle for sequential tests," which we then apply to some
existing sequential multiple testing procedures to give simplified
understanding of their FWER control. Next the principle is applied to derive
two new sequential multiple testing procedures with provable FWER control, one
for testing hypotheses in order and another for closed testing. Examples of
these new procedures are given by applying them to a chromosome aberration data
set and to finding the maximum safe dose of a treatment
