The particle se with a verb can be assigned the following afuns: AuxT, Obj, AuxR.
The particle si with a verb can be assigned the following functors: AuxT, Obj, Adv, AuxO.
The assignment of these functions is determined by the verbs in question. With many verbs more than a single assignment is possible, and the final decision is to be made on the basis of the given context.
Both particles are suspended on the verb to which they belong, irrespective of the function they carry.
If a noun is derived from the given verb (snažit to try → snažení trying), the particles are always assigned afun Atr without regard to what kind of afun they would get if they were attached to the source verb.
SE 1 This is a case of "reflexivum tantum", AuxT: the verb does not occur without the particle or if the particle is taken away, the verb has a different meaning: bojí se s/he-is-afraid, snaží se s/he-tries, směje se s/he-laughs, setkali se they-met.
The same solution is accepted for some derivatives of the "manner of the action": nadřel se he-drudged.
If the construction corresponds to the condition under SE 1, the particle se is assigned afun AuxT and the possibility to assign it an Obj is not taken into account.
v novinách se píše o projevu in newspapers they write about the speech, diskutovalo se o objevu a discovery was discussed, přirozený jazyk se popisuje formálními prostředky natural language is described by formal means,
a construction of "disposition" (medio-passive): matematika se mu studuje lehce mathematics is easy to study for him, v téhle troubě se dobře peče it is easy to bake in this oven, ta kniha se snadno prodává the book sells well,
also causatives of the following type belong here: léčím se u prof. Myslivečka I undergo medical treatment at prof. Mysliveček, holí se/stříhá se v Šarmu he shaves (himself)/has his haircut in Šarm, obléká se u Nehery he dresses (himself) at Nehera.
We use the codition (1) only if the situation is completely clear.
SI 1 This is an analogy to SE 1: AuxT is assigned only with the dative si: pospíšit si to hurry up, vážit si to respect something/somebody, postesknout si to complain, pamatovat si to remember.
SI 3 This is an analogy to SE 4, but we have decided to assign Adv in those cases in which si has the function of a free dative (dative of benefit); a paraphase by for oneself or by one's is possible: upevnit si (postavení) to strengthen one's position, upravovat si (vlasy) to set one's hair, brousit si (zuby) set one's heart upon, vydělat si (peníze) to earn money, uchovat si (postavení) to keep (one's position).
SI 4 In this function, si is assigned AuxO; it is somewhat superflous, and can be deleted without a loss of meaning or grammaticality: jít si na výlet to go for a trip, mazat si to domů to hurry home, počkat si na někoho to have to wait for somebody, už si odpracoval dvě hodiny he has already worked off two hours.