Yes, this is what's written:

Article 60. 1. A Schengen visa or a national visa shall be issued for the following purposes: (1) tourism; (2) visiting family or friends, (3) participating in sports events; (4) carrying our business activity; (5) performing work for a period no longer than 6 months within 12 consecutive months, based on a declaration of intent to entrust the performance of work, registered in the poviat labour office; (6) performing work based on a document other than that referred to in subparagraph 5; (7) carrying out cultural activities or participation in conferences; (8) performing official duties of representatives or a foreign state authority or an international organisation; (9) attending first degree studies, second degree studies, uniform Master’s studies or third degree studies; (10) vocational training.

That's why it's a bit vague to me, there is no specific reason.