Symbol Loading Unit (SLU), the ‘matchbox’ that feeds EVM candidate information

• Recently, SC rejected the plea for 100% verification of Voter Verifiable Paper Audit Trail (VVPAT) slips against the Electronic Voting Machine (EVM) count.
• The Supreme Court directed the Election Commission of India (ECI) to “seal and secure” the Symbol Loading Unit (SLU) for 45 days after the declaration of election results.

Key highlights

• Currently, only the three components of the EVM - the ballot unit, control unit, and VVPAT - are stored for 45 days after the results.
• 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.

What is a Symbol Loading Unit (SLU) and how does it work?

• Symbol Loading Units (SLUs) were introduced around the same time as VVPATs
• VVPATs help voters verify their votes - they see a slip with a printed image of the party symbol they voted for.

How SLU works.

• But for the VVPAT to print a symbol correctly, information pertaining to the list of candidates and their symbols must be loaded on to the VVPAT machine in the correct order.
• This is where the Symbol Loading Unit, or SLU, comes in.
• The SLU is used to load the symbols of the candidates onto the VVPAT.
• It is a matchbox-sized device that is first connected to a laptop or personal computer, from which a symbol loading application is used to load a bitmap file containing the candidates’ names, serial numbers, and symbols.
• The SLU is then connected to the VVPAT to transfer that file on to the paper audit machine.
• This is done under the supervision of a district election officer.

What happens to an SLU after symbols are loaded?

• Typically, a small number of SLUs are enough to load symbols onto all VVPATs for a seat.
• According to EC officials, it takes an SLU two to three minutes to load each VVPAT.
• Once the symbol-loading is complete, the SLUs are handed over to the concerned district election officer for safekeeping.
• Thus, in a multi-phase election like the ongoing one for the 18th Lok Sabha, an SLU is typically reused after one phase of polling to load symbols onto VVPATs meant for other seats in subsequent phases.

What has the SC said about the SLUs?

• The court has said that the SLUs should be sealed and stored immediately after the symbol-loading process for a seat is complete.
• It must be stored for a period of 45 days after the declaration of results, so that it can be opened and examined like EVMs in case of an election petition.

And what has the top court said about microcontrollers?

• In an unprecedented move, the court has allowed candidates to seek verification of EVM software.

What happens if the microcontrollers, upon verification, are found tampered?

• The court has only said that if any tampering is found, the candidate will be refunded the cost of verification.

What changes on the ground?

• Nothing changes for the voter.
• The ECI will now have to store SLUs for 45 days after voting.
• To reserve one SLU exclusively for one seat, it will need to order more SLUs.
• Also, the ECI will have to examine whether the Representation of the People Act of 1951 has to be amended.
• During this period, the EC machinery does not touch the EVMs. If these machines now need to be unsealed for verification purposes, the poll panel will have to determine how this can be accomplished.