You are to maintain at least the standard NS hair cut.
That is... Smart. Neat. Short. Tidy. Pleasant. Presentable.
Even NSmen/ reservists are also subject to the same NS standard, discipline and regimentation when they report back for in-camp training (ICT).
In unit, you no longer have to fulfill the 'tekong haircut'. Just make sure you dont get caught for long hair!
cheers