minor difference in how the part number magic is made

tests/FILEFORMAT

@@ -27,9 +27,9 @@ this response is sent. If not, the connection will be kept persistant.
 Send back this contents instead of the <data> one. The num is set by:
 A) The test number in the request line is >10000 and this is the remainder
 of [test case number]%10000.
-B) The request was HTTP and included digest details, which sets NUM to 1000.
-C) If a HTTP request is NTLM type-1, it sets num to 1001
-D) If a HTTP request is NTLM type-3, it sets num to 1002
+B) The request was HTTP and included digest details, which adds 1000 to NUM
+C) If a HTTP request is NTLM type-1, it adds 1001 to num
+D) If a HTTP request is NTLM type-3, it adds 1002 to num
 </dateNUM>
 <datacheck [nonewline=yes]>
 if the data is sent but this is what should be checked afterwards. If