Translation of numeric entities

Hi
 
Does anyone know whether I can stop Tidy from translating numeric entities
into actual characters?  For example, ' translates into an apostrophe
rather than retaining the '   ÷ to a +  etc.  Config is below,
although I have played around with different settings with the same result -
ie the entities are converted to actual characters.
 
indent-spaces: 4
indent: auto
indent-attributes: yes
tidy-mark: no
show-errors: 0
show-warnings: false
input-encoding: latin1
output-encoding: ascii
numeric-entities: yes
 
Thanks
Graham A.