Unmasking? The Real Story Is When Flynn Was Not Masked in the First Place

The second kind of FISA collection occurs under Section 702 of the statute. It brings under FISC jurisdiction various intelligence-collection programs that target categories of non-Americans outside the United States. These foreigners also communicate with Americans, so the latter are incidentally intercepted.

Under federal law, both kinds of FISA collection are subject to so-called minimization procedures. These aim to safeguard the privacy of Americans who have been incidentally monitored. When raw intelligence is refined into intelligence reports (including transcripts of recorded conversations) that are disseminated to U.S. officials, the identities of these Americans do not appear. Rather, a designation such as “U.S. Person” is substituted — the “mask,” as it were.

https://www.nationalreview.com/2020/05/michael-flynn-unmasking-real-story-is-when-he-was-not-masked-in-the-first-place/