The Allen and Greenough is still under construction;
so some links may not work quite the way you would expect.
23. Adverbs, Prepositions, Conjunctions, and
Interjections are not inflected and are called Particles.
NOTE: The term Particle is sometimes limited to such words as
num, -ne, an (interrogative),
nón, ne (negative),
si (conditional), etc., which
are used simply to indicate the form or construction of a sentence.