-During the second pass, the file size is cut in half. In that same fairyland world, this means 200 files and 200 file marks.
-.PP
-In both passes the total amount of data written is summed as well as the number of file marks written. At the end of the second pass, quoting from the code:
-.PP
-* Compute the size of a filemark as the difference in data written between pass 1 and pass 2 divided by the difference in number of file marks written between pass 1 and pass 2. ... *
-.PP
-So if we wrote 1.0 GBytes on the first pass and 100 file marks, and 0.9 GBytes on the second pass with 200 file marks, those additional 100 file marks in the second pass took 0.1 GBytes and therefor a file mark is 0.001 GBytes (1 MByte).
-.PP
-Note that if the estimated capacity is wrong, the only thing that happens is a lot more (or less, but unlikely) files, and thus, file marks, get written. But the math still works out the same. The \-e flag is there to keep the number of file marks down because they can be slow (since they force the drive to flush all its buffers to physical media).
+Volume capacity is determined by writing one large file until an error, interpereted as end\-of\-tape, is encountered\&. In the next phase, about 100 files are written to fill the tape\&. This second phase will write less data, because each filemark consumes some tape\&. With a little arithmetic,
+\fBamtapetype\fR
+calculates the size of these filemarks\&.