noun
old style; old format; old-structure form
Refers to something that follows an older pattern, structure, or convention, often contrasted with a newer version.
この書類は旧形式なので、新しい様式に書き直してください。
This document is in the old format, so please rewrite it in the new style.
旧形式の契約書は法的に問題がある場合がある。
Old-style contracts may sometimes have legal issues.
旧式 also means 'old style' but often implies outdated or obsolete, whereas 旧形式 is more neutral and simply refers to an older form.
Compound of 旧 (old) and 形式 (form, format). The reading is the standard on'yomi combination.