Yes, that's right. On the flip side, the characters also have access and can read what other npcs are writing to each other: teachers use it to post reminders about school assignments and the students mostly use it for homework help or making after school plans. For the TDM, characters are able to read conversations up to one year back, but if they ask an npc about it, they'll be told that the forum is wiped at the start of each school year.