Declaration: TParticles.ClassNames[ClsIx: integer]: string;
The array property ClassNames allows to access the name of a particular class which is specified by the parameter ClsIx (valid range: 1..NClasses). If you assign a name to a non-existent class (i.e. if the ClsIx is less than 1 or greater than NClasses) the call will be ignored on write or return an empty string on read.

Please note the subtle difference of the properties ClassNames and ClassIDs. While ClassNames should contain a readable identifier of the class ("nice name") the property ClassIDs is a more technical one and serves to uniquely identify a particular class. ClassNames is typically used to display the names of classes, which ClassIDs is used to address a particular class.

Hint: In order to access the particles currently loaded in the particle editor you can use the pre-declared global variable PEData.