[O] Marking specific elements for folding?

[Yu]

Hello!

I was wondering, if there is a way to mark specific elements for
staying folded unless explicitly shown. Reading the manual I only
found possibilities to control the global folding of sections and
blocks in general.

However, what I want to do is:
- Embed a table of numerical data in my org-mode file.
- Perform calculations on the data, using the spread sheet capabilities.
- Plot the data, preferably using a (probably lengthy) gnuplot script.
- Export only the result graph.

However, the calculations are usually not wanted to be seen, when
looking at the file, so I'd like to specify, that this specific table
and this specific gnuplot code block are to be folded by default.

Is there some way to achieve this?