Lock-in of promoters' contribution restricts transferability, differentiating minimum and excess holdings under public issue rules. Regulation 36 imposes a lock-in on specified securities held by promoters in a public issue, treating minimum promoters' contribution (including certain alternative investment fund contributions) as subject to a longer lock-in measured from the later of the date of commencement of commercial production or allotment, while promoters' holdings in excess of the minimum are subject to a shorter lock-in; specified excess contributions under the proviso to regulation 34 are excluded. The date of commencement of commercial production is defined as the last date of the month in which production is expected per the offer document.