Companies based in Sikkim and the Andaman and Nicobar islands can now file offer documents for public issues of up to 500 crore rupees with SEBI's Eastern Regional office in Kolkata, the market regulator said on Wednesday.This comes into effect for all draft offer documents for issues which are filed with SEBI on or after 27 August 2012.For offer sizes higher than 500 crore rupees, the documents need to be filed at SEBI's main office in Mumbai.