I used:

Description_TOS = Description_TOS.Open(Description_FI)

to write a TextArea contents to disk and unwanted result:
just like if I used Append…

So, I changed the first line to

Description_TOS = Description_TOS.Create(Description_FI)

and it works as intended.

Did I notice (before) there is no Append ? (I do not know)

This can be good to know (both: avoid the error / how to append text).

BTW: yes, I do not recall how long I write code with TextOutputStream :wink:
(so I recall gool old BASIC from 40 years ago)…