+"dumpoverlay.lsp"
+
+; E.g., consider a fusefile stack D:A:B:C with overlays A:B:C over D.
+; That stack would have been built in a succession of first using
+; stack D:A where changes are collated into overlay A, as in the
+; following setup:
+;
+; $ fusefile E -overlay:A D
+; ... writes to E (= D:A) goes into A
+; $ fusermount -u E
+;
+; Note that the "D" part might in reality be a more complex
+; composition of several file fragments, but in these examples we
+; refer to it simply as "D".
+;
+; Continuing the example, the new stack D:A:B is used for collating
+; further changes into B, as in the following setup:
+;
+; $ fusefile E -overlay:A:B D
+; ... writes to E (= D:A:B) actually goes into B
+; $ fusermount -u E
+;
+; Later again, the stack D:A:B:C is used for collating changes into C,
+; as in the following setup:
+;
+; $ fusefile E -overlay:A:B:C D
+; ... writes to E (= D:A:B:C) actually goes into C
+; ...
+; $ fusermount -u D
+;
+; At that point, one may decide to merge down the overlay C onto a
+; D:A:B fusefile and thereby add the C changes over B.
+;
+; $ fusefile E -overlay:A:B D
+; $ merge-overlay E C
+; $ rm C
+; $ fusermount -u E
+;
+; Or alternatively, one may decide to merge down the B changes without
+; C onto a D:A fusefile and thereby add B to A.
+;
+; $ fusefile E -overlay:A D
+; $ merge-overlay E B
+; $ rm B
+; $ fusermount -u E
+;
+; In the latter case the updated overlay A includes the writes
+; collated in B and thus now the stack D:A:C would be the same as the
+; previous stack D:A:B:C.
+;
+; End of example.