Tense in Sargaĺk

Sargaĺk's tense system (ignoring the topic of aspect) has a few complications:

Different basic underlying systems for different verbs
Some verbs in Sargaĺk have a past-present-future system going, e.g. 'to be', 'to go', 'to snow', 'to prepare for a fishing excursion', 'to remember', 'to remain', 'to vow'. Some verbs have a past vs. non-past system, and some have a non-future vs. future system. Further, some verbs have hodiernal and even hesternal forms.

The poverty of marking
If we count all forms distinguished or permitted by at least one verb, we reach about a dozen tenses:

hodiernal non-past, hodiernal past, hodiernal future, hodiernal non-future, hodiernal present, hodiernal future, hesternal, regular future, far future, regular past, far past, present, wide present

Despite this, there are only these morphemes in use:

-mab-:

future  or non-past, when reduplicated it can indicate hodiernal or crastinal future, depending on the verb.

-nek'-

past or non-future, when reduplicated it can indicate hodiernal or hesternal past, depending on the verb.

The hodiernal non-past or non-future is often unmarked with a tense marker, but this does differ with some verbs. 

A few verbs do not form the basic tenses by suffixes, but by stem suppletion, e.g.

non-past sab, past kasa: raise, heighten, lift
non-past rorn, past jita: sleep
future: ingar, non-future nasan, grow, turn, (become)
future: p'ulk, non-past: uluŋ, cease, give up, give in,

These verbs distinguish the greatest number of tenses: both stems can combine with both the future/non-past and with the past/non-future marker. The resulting samnek'- signifies hodiernal past, whereas kasnek' signifies a hesternal past, kasmab signifies a hodiernal fuure, samab signifies a crastinal future. Reduplication leads to far past or future tenses.

Aspect

Aspect has certain dedicated markers; however, derivative morphology sometimes interacts with aspect markers - either by making them superfluous, or by causing other particular markers to be used. Aspect is somewhat lexical.

Comparative Linguistics
In Dairwueh, '-mab' has a cognate in 'maptə', soon (perfective), and 'maviŋa' tomorrow. 'Mab' thus clearly relates to future spans of time in Dairwueh.

-nek' has several cognates in both Dairwueh and Bryatesle - ynykt is yesterday evening in Bryatesle, usually in the ablative definite ynykənt, 'a duration during last evening)'. There's also an adverb 'any(k)tmin', which signifies at some indeterminate time during the last few days. In Dairwueh, you get ənken 'yesterday', as well as -ənk suffixed to numbers signifying 'days ago', and the adverb nəkne, 'a while ago'. For both languages, there's thus evidence indicating that -nek relates quite clearly to a time during the previous day.