kənstɹˈʌktɪŋ ɐn ˌoʊvɚlˈeɪ pɹˈoʊɡɹæm ɪnvˈɑːlvz mˈænjuːəli dᵻvˈaɪdɪŋ ɐ pɹˈoʊɡɹæm ˌɪntʊ sˈɛlfkəntˈeɪnd ˈɑːbdʒɛkt kˈoʊd blˈɑːks kˈɔːld ˌoʊvɚlˈeɪz ɔːɹ lˈɪŋks, dʒˈɛnɚɹəli lˈeɪd ˈaʊt ɪn ɐ tɹˈiː stɹˈʌktʃɚ.
Constructing an overlay program involves manually dividing a program into self-contained object code blocks called overlays or links, generally laid out in a tree structure.