Thanks Snail, the mission is "Small Deadly Space".
I downloaded FS1DEMO again from Volition's site and extracted mission files to confirm the title.
I found that "Small Deadly Space" was already ported in FSPort mission pack as a part of FS1 campaign.
And I managed to play it under SCP as single mission.
Thanks for porting.
However, I felt something different.
I remember oridinal DEMO mission takes more long minutes before attacking cargo.
I like this tension before battle and attending friendly fightres.
The ported one may be shortened this sequence, I guess.
I think this editting is from FS1 oridinal canpaign.
Not from porting.
Anyway, I recently working GTF Theseus.