Explain the default key field comparisons.
@@ -255,6 +255,14 @@ kgtk ifexists --input-file examples/docs/ifexists-file1.tsv \
| p2 | peter | zipcode | 12040 | home | |
| p3 | peter | zipcode | 12040 | work | 6 |
+!!! note
+ Since both the input file and the filter file are KGTK edge files, the
+ default key field comparisons are:
+
+ > input.node1 == filter.node1 and
+ > input.label == filter.label and
+ > input.node2 == filter.node2
+
### Filter an Edge File on a Node File
```bash
