should i restrict portraitupdsidedown mode for ipad

i think my ipad app does not require a upside down 开发者_如何转开发mode because it changes the side buttons' locations. am i correct ? this is not a game app. An app meant for reading documents.

The HIG strongly recommends supporting upside-down mode. I think that a document reader especially needs this mode.

http://developer.apple.com/library/ios/ipad/#qa/qa2010/qa1689.html