R. S. Ginzburg, S. S. Khidekel, G. Y. Knyazeva, A. A. Sankin a course in modern english

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3. 
   collectivity, e.g. -age, -dom, -ery (-ry), etc. (freightage, officialdom, peasantry, etc.);
   
4. 
   diminutiveness, e.g. -ie, -let, -ling, etc. (birdie, girlie, cloudlet, squireling, wolfling, etc.).
   

4) Still another classification of suffixes may be worked out if one examines them from the angle of stylistic reference. Just like prefixes, suffixes are also characterised by quite a definite stylistic reference falling into two basic classes:

1. 
   those characterised by neutral stylistic reference such as -able, -er, -ing, etc.;
   
2. 
   those having a certain stylistic value such as -oid, -i/form, -aceous, -tron, etc.
   

Suffixes with neutral stylistic reference may occur in words of different lexico-stylistic layers e.g. agreeable, cf. steerable (steerable spaceship); dancer, cf. transmitter, squealer; ¹ meeting, cf. monitoring (the monitoring of digestive processes in the body), etc. As for suffixes of the second class they are restricted in use to quite definite lexico-stylistic layers of words, in particular to terms, e.g. rhomboid, asteroid, cruciform, cyclotron, synchrophasotron, etc.

5) Suffixes are also classified as to the degree of their productivity.