In general, there are a few types of special occation dress codes. The most formal dress code is White tie (swe: Högtidsdräkt) (ceremonial dress, evening dress, full evening dress) which means tailcoat, mess dress/mess uniform or national/traditional costume. Civilian ceremonial dress means white tie (tailcoat a.s.o). The tailcoat shall be worn together with a white waistcoat and white bow tie at ceremonies with ladies present, and black waistcoat but still a white bow tie at gents dinners and fraternity ceremonials.
Some time ago there was no need to specify dress codes on invitations to weddings and similar occasions since white tie always were the dress code for afternoons and morning coats/cutaways were used in the mornings. Today, if unsure about the dress code, consult the host/hostess.
Morning coat/cutaway (swe: Jaquette) is mostly used at weddings, and should be worn no later than 15.00. The morning coat should be worn together with a grey waistcoat, grey striped trousers and a neck tie with grey patterns if wearing a traditional, white shirt with double collars, or a platstron with grey patterns if wearing a dress suit shirt.
Black tie (swe: Smoking) (dinner jacket suit, tuxedo, smoking jacket or in military terms sometimes mess undress) is considered to be more informal. It is commonly used at birthday anniversaries and bigger or smaller parties. A black dinner jacket is worn together with a black bow tie (or needless to say, blue bow tie if using a blue dinner jacket). Waistcoat or cummerbund are not mandatory but can be used if desired.
Informal (swe: Kavaj) dress code means dark suit and is common for guests at weddings, christenings, informal dinners and similar activities. At funerals, close relatives should use white ties, and other attendees black ties. During recent years, dress codes like "summer clothing" (swe: sommarfin) and "cocktail clothing" has started to appear on invitations - which in most cases suggests that an extra consultation with the host/hostess could be a good idea.