*Classesmustbenamedbyfollowingthenamingconventions.*Thebraceisalwayswrittenrightaftertheclassname(orinterfacedeclaration).*EveryclassmusthaveadocumentationblockthatconformstothePHPDocumentorstandard.*Anycodewithinaclassmustbeindentedfourspaces.*OnlyoneclassispermittedperPHPfile.*PlacingadditionalcodeinaclassfileisNOTpermitted.Thisisanexampleofanacceptableclassdeclaration:<codetype="php">/** * Documentation here */classDoctrine_SampleClass{// entire content of class// must be indented four spaces}