diff --git a/src/doc/manual/developer-guide/objects.txi b/src/doc/manual/developer-guide/objects.txi
index d27da1107..e8e4c11cc 100644
--- a/src/doc/manual/developer-guide/objects.txi
+++ b/src/doc/manual/developer-guide/objects.txi
@@ -324,6 +324,10 @@ a word of memory and which is between the values
 @code{bignum} is any integer which is not a @code{fixnum} and it is only
 constrained by the amount of memory available to represent it.
 
+ECL code{@integer} subtypes @code{fixnum} and @code{bignum} are defined
+as built-in classes, so it is possible to specialize to them generic
+functions.
+
 In ECL a @code{fixnum} is an integer that, together with the tag bits,
 fits in a word of memory. The size of a word, and thus the size of a
 @code{fixnum}, varies from one architecture to another, and you should
@@ -399,6 +403,12 @@ appropriate size. Signals an error if @var{o} is not of fixnum type.
 @coderef{fixnint} additionally ensure that @var{o} is not negative.
 @end deftypefun
 
+@subheading Floats
+
+In ECL @code{float} subtypes @code{single-float}, @code{double-float}
+and @code{long-float} (on supporting platforms) are defined as built-in
+classes, so it is possible to specialize to them generic functions.
+
 @subheading Characters
 
 @cfindex --enable-unicode [32|16|no]