Sigma Trust Google Docs Lockdown is a Chrome extension that removes the spelling and grammar features from Google Docs. This extension is designed to work alongside Safe Doc, allowing Google Docs to be used for exams. Once Safe Doc has disabled the spelling and grammar check features, Sigma Trust Google Docs Lockdown hides the menu so that the features cannot be re-enabled.

In addition to removing the spelling and grammar check, Sigma Trust Google Docs Lockdown also disables several other features. This includes the Insert, Tools, Add-Ons, and Help menus, as well as toolbar buttons for Insert Image, Insert Comment, and Insert Link. The header buttons, which include the Share controls, are also hidden. Furthermore, the extension intercepts the 'contextmenu' event to prevent the use of the Google Docs contextual menu, which contains Explore and Define commands.

It's worth noting that Sigma Trust Google Docs Lockdown will reapply the above settings if the page is refreshed or if the account is logged out and back in again. This ensures that the lockdown remains in effect even after a user logs out and logs back in.