There are 2 main definitions of interline in English:

interline1

Line breaks: inter|line
Pronunciation: /ɪntəˈlʌɪn
 
/

verb

[with object]
Insert words between the lines of (a document or other text): the writing was overwritten and interlined by many hands

Origin

late Middle English: from medieval Latin interlineare, from inter- 'between' + Latin linea 'line'.

Definition of interline in: