Devibhagavatapurana 3.18.41

3.18.41

svayaṃvarastu trividho vidvadbhiḥ parikīrtitaḥ |
rājñāṃ vivāhayogyau vai nānyeṣāṃ kathitaḥ kila ||

The Svayambara of the royal family, the Pundits say, is of three kinds:-- lst Ichchhâ Svayambara (optional); 2nd Panya Svayamvara by fulfilling a promise, e.g. Râmachandra broke in two the bow of S’iva and married Sîtâ; 3rd the Svayambara, preferring one who will prove the strongest hero by one’s own prowess. Of these three kinds of Svayambaras, the king Subâhu preferred Ichchâ Svayamvara (according to the bride's free choice).
Accordingly the king employed many artisans, had platforms covered with beautiful carpets and big halls decorated beautifully in various ways.