SYMBOL LOADING UNIT (SLU) (Syllabus: GS Paper 2 – Polity)

Context: Recently, the Supreme Court dismissed the plea for 100% verification of Voter Verifiable Paper Audit Trail (VVPAT) slips alongside Electronic Voting Machine (EVM) counts but instructed the Election Commission of India (ECI) to safeguard the Symbol Loading Unit (SLU) for 45 days post-election result declaration.

Voter Verified Paper Audit Trail (VVPAT)

• About: It is an independent system [consists of two parts, namely, VVPAT Printer and VVPAT Status Display Unit (VSDU)] attached with the Electronic Voting Machines that allows the voters to verify that their votes are cast as intended.

Electronic Voting Machines (EVM)

• About: EVMs facilitate candidate selection through button presses.

Symbol Loading Unit (SLU)

• About: SLUs are essential components in the functioning of Voter Verifiable Paper Audit Trail (VVPAT) systems, introduced concurrently with VVPATs approximately a decade ago.
• Purpose of VVPATs: It  allow voters to verify their votes by displaying a printed slip containing the symbol of the chosen party.
• Role of Symbol Loading Units (SLUs): These are crucial for ensuring the accurate printing of symbols on VVPAT slips.
• Integration with VVPAT Systems: The introduction of VVPATs necessitated the utilization of SLUs for loading candidate symbol information onto the VVPAT machine.
• Loading Procedure: The SLU is connected to a laptop or personal computer, where a symbol loading application is used to load a bitmap file containing candidates’ names, serial numbers, and symbols.
• Data Transfer: Once the symbol information is loaded onto the SLU, it is connected to the VVPAT machine to transfer the file onto the paper audit machine.
• Storage Duration: Currently, only the three components of the EVM  the ballot unit, control unit, and VVPAT  are stored for 45 days after the results. 

o This is the first time that SLUs, used to load candidate symbols onto the VVPATs, will also be available for examination along with the EVMs if a candidate challenges the results by filing an election petition in court.