Rather, reverse contig refers to a possible alternate location that a contig might have if it were reversed. See the image below as an illustration.

In the above image, a locus anchors a clone which indirectly anchors a contig. This clone is in the first few beginning bands of the contig, according to the FPC program. We call this default FPC placement the forward contig. The example contig in the above image happends to extends out to the right of the locus in this default FPC placement.

However, the default FPC placement could be incorrect. The example clone could possibly be in the last few bands of the contig instead of being in the first few bands, as illustrated in the image above. We call this alternate placement the reverse contig. In the above example, the reverse contig extends out to the left of the locus.

If the clone anchor is in the middle of the contig, then the forward and reverse locations would be the same.

If a contig has more than one clone anchor, then it is possible that only the forward direction, or only the reverse direction, is appropriate. In our database, if the reverse contig is the only appropriate direction, we call the contig flipped.