+;;; (In 0.pre7.48, the low-level object layout of SYMBOL on the
+;;; non-X86 ports changed. I forgot to bump the fasl version number:
+;;; I only have an X86.. -- WHN)
+;;; 19 = sbcl-0.pre7.50 deleted byte-compiler-related low-level type codes
+;;; 20 = sbcl-0.pre7.51 modified names and layouts of
+;;; physical-environment-related structures in the compiler
+;;; 21 = sbcl-0.pre7.62 finally incremented the version after several
+;;; incompatible changes in earlier versions: many many symbols
+;;; renamed, changes in globaldb representation of constants
+;;; and inline functions, and change in the value of
+;;; INTERNAL-TIME-UNITS-PER-SECOND
+;;; 22 = about a zillion changes between sbcl-0.pre7.62 and
+;;; sbcl-0.pre7.133, during which time it seemed too much
+;;; trouble to increment the counter
+;;; 23 = sbcl-0.7.0.1 deleted no-longer-used EVAL-STACK stuff,
+;;; causing changes in *STATIC-SYMBOLS*.
+;;; 24 = sbcl-0.7.1.19 changed PCL service routines which might be
+;;; called from macroexpanded code