Wikipedia
Captain-commandant is a company grade of commissioned officer rank in the air component, land component, the old Belgian Gendarmerie and medical component of the Belgian Armed Forces. A kapitein-commandant (Dutch) or capitaine-commandant (French) ranks directly above a captain and immediately under a major. Officers of this rank usually serve in staff functions or more rarely as small unit commanders ( squadron, company). The insignia are three pips under a narrow stripe for the land component, three blue stripes with navy curl for the air component and three gold stripes with navy curl for the medical component.
In the naval component, the rank is called luitenant ter zee eerste klasse or Lieutenant de vaisseau de première classe (" ship-of-the-line lieutenant first class"), and the insignia is two and a half gold stripes with a naval curl.