N302 in X12 270/271: A Field Guide to Address Information
N302 only appears when an address needs a second line, which makes it the element most likely to be skipped entirely in hand-built test files — and the one most likely to break a display template the first time a real suite number shows up.
N302 is the second element of the N3 segment in an X12 271 response — an optional free-form field that carries additional address detail, such as a suite, unit, floor, or PO box, when a single line isn't enough.
What this element carries
Example
N302 = Suite 210, the secondary address line that follows the street name in N301. Synthetic 271 response data.
Where this trips people up
Display and mailing templates built against test data where N302 is always empty tend to hardcode a single-line address layout. The first production address with a populated N302 either gets dropped from the rendered output or gets awkwardly appended to the end of N301 with no line break, and both mistakes look fine in a demo where nobody happens to live in a suite.