Index: README.EXT
===================================================================
--- README.EXT	(revision 26152)
+++ README.EXT	(working copy)
@@ -99,11 +99,12 @@
 FIX2INT() macro or FIX2LONG().  Though you have to check that the
 data is really FIXNUM before using them, they are faster.  FIX2LONG()
 never raises exceptions, but FIX2INT() raises RangeError if the
-result is bigger or smaller than the size of int.
-There are also NUM2INT() and NUM2LONG() which converts any Ruby
-numbers into C integers.  These macros includes a type check,
-so an exception will be raised if the conversion failed.  NUM2DBL()
-can be used to retrieve the double float value in the same way.
+result is bigger or smaller than the size of int.  This is because
+internally it can be up to 63 bits, whereas a typical int is typically
+only 32 bits. There are also NUM2INT() and NUM2LONG() which convert any 
+Ruby numbers into C integers.  These macros include a type check, so 
+an exception will be raised if the conversion failed.
+NUM2DBL() can be used to retrieve the double float value in the same way.
 
 You can use the macros
 StringValue() and StringValuePtr() to get a char* from a VALUE.