One of the tasks of the suffix "-dir" is to express official/formal notifications. You usually see in the official places (for ex: in the banks, public areas, in the work places, in academical texts etc. etc.) the sentences ends with "-dir". The task of official notifications is why they end with "-dir".

sigara (the cigarette), içmek (to drink), yasak (1forbidden, 2the prohibition)

Sigara içmek yasak. (No smoke. (direct: It´s forbidden to smoke.))

If you want to make it in the official meaning:

yasak+dır---------->yasaktır [remember the hardening of consonant]

Sigara içmek yasaktır. (No smoke. (direct: It´s forbiddent to smoke.))

hesap (1the account, 2the calculation)

para (the money)

kalmak (1to stay, 2to remain)

hesap+nız+da------------>hesabınızda (in your account)

kal+ma(negative)+mış+dır->kalmamıştır (it hasn´t remained)

"-miş" leaves the meaning of unknownness/unclearness when it comes together with "-dir". Because "-dı" which iis simple past suffix can´t be used with "-dir". It´s certainly wrong to write "-didir".

Hesabınızda para kalmamıştır. (No money in your account more. (direct: Any money hasn´t remained in your account.))

geçici (temporary), şifre (the password), yedek (substitute, reserve) e-posta (the e-mail), göndermek (to send)

geçici şifre (the temporary password)

geçici şifreniz (your temporary password)

e-posta+nız+a(dative)----->e-postanıza (to your e-mail)

gönder+il(passive)+miş+dir->gönderilmiştir (it has sent)

Geçici şifreniz yedek e-postanıza gönderilmiştir. (Your temporary password has been sent to your substitute e-mail.)

toplantı (the meeting, the gathering), katılmak (to join), üye (the member)

geç (late), dokuz (nine), yer (1the place, 2the ground, 3the earth),

hazır (ready), hazır bulunmak (to be present)

gerekmek (to need, to be needed)

toplantı+a(dative) katıl+acak(verbal adj.) üye+ler(plural)+miz+in(genitive)

-->toplantıya katılacak üyelerimizin (our members which will join the gathering)

toplantı yer+i(poss.)------>toplantı yeri (the gathering/meeting place) [ind.poss.determ.]

toplantı yer++de(loc.)---->toplantı yerinde (in the meeting place)

en geç saat 9´da (at 9 o´clock latest)

en geç saat 9´da hazır bulunmak (to be present at 9 o´clok latest)

bulun+ma(vrb.noun)+ları(poss.of3rdplural)-->bulunmaları

gerekmek+de(locative)+dir-->gerekmektedir (it needs (direct: it is at to be needed))

Toplantıya katılacak üyelerimizin toplantı yerinde en geç saat 9´da hazır bulunmaları gerekmektedir. (Our members which will join the meeting need to be present at the meeting place at 9 o´clock latest.)

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Suppose you read these sentences in an encyclopedia. Probably you will see the sentences end with "-dir":

Ağrı Dağı Türkiye´nin en uzun dağıdır. (The Mount Ağrı is the highest mountain of Turkey.)

Türkiye Cumhuriyeti´nin resmî dili Türkçedir. (The official language of the Turkish Republic is Turkish.)