The filter |charset2unicode applied to a text tag transforms a string into unicode entities 
For example, from a #DESCRIPTION tag that normally returns the following html source:
2 est supérieur à 1 & it is noted: 2 > 1
we will use:
[(#DESCRIPTIF|charset2unicode)]
which will return the html source code:
2 est "supérieur" à 1 & c’est noté : 2 > 1
The interesting point about this filter is that it does not impact the html tags.