The document contains responses to frequently asked questions about the 2010 Philippine elections and the Precinct Count Optical Scan (PCOS) machines. The PCOS machines can operate for at least 16 hours on battery power if disconnected from the main electricity source. Once a ballot is marked, mistakes cannot be corrected or the ballot replaced. Voters must mark their ballot carefully. While all systems can potentially be hacked, the PCOS machines are designed to be difficult to hack. They operate stand-alone to deny access and are only online for a maximum of two minutes when transmitting results. It would take several days to crack the encryption used, so hacking is unlikely to succeed.