Ask HN: Do you use any plain text calendar strategies/solutions?

I recently switched over to using todo.txt as well as plain text accounting. I have my text files synced across my devices using Syncthing; I edit with Vim on my computer and Simpletask on my phone. But I am dissatisfied with my calendar and I wonder if anyone has tried approaching the calendar in the same was as todo.txt or PTA. Thank you & Namaste