Republicans and Democrats, and groups sympathetic to each, spend millions on sophisticated technology to gain an advantage. But sometimes, a simple coding mistake can lay bare documents and data that were supposed to be concealed from the prying eyes of the public. Such an error by the Republican Governors Association recently resulted in the disclosure of exactly the kind of information that political committees given tax-exempt status usually keep secret, namely their corporate donors and the size of their checks. The documents, many of which the Republican officials have since removed from their website, showed that many of America's most prominent companies, from Aetna to Walmart, had poured millions of dollars into the campaigns of Republican governors since 2008. "This is a classic example of how corporations are trying to use secret money, hidden from the American people, to buy influence, and how the governors association is selling it," said Fred Wertheimer, the president of Democracy 21. The trove of documents, discovered by watchdogs at the Democrat-aligned Citizens for Responsibility and Ethics in Washington, or CREW, sheds light on the secretive world of 501(c)(4) political groups, just as the battle over their future intensifies. The tax-exempt Republican Governors Public Policy Committee is not required to disclose anything, even as donors hit the links, rub shoulders and trade policy talk with governors and their top staff members. In a tit for tat, the Republican association unearthed documents from the Democratic Governors Association that also name corporate donors and the benefits.