Here is my "include" list:
#include <Mstn\MdlApi\MdlApi.h>
#include <DgnGeoCoord\DgnGeoCoord.h>
#include <DgnGeoCoord\GeoCoordErrors.h>
#include <Mstn\MstnPlatformAPI.h>
#include <dgnplatform\textHandlers.h>
#include <dgnplatform\dimensionHandler.h>
#include <Mstn\cmdlist.r.h>
#include <RmgrTools\Tools\msstrlst.h>
#include <DgnPlatform\DgnECProviders.h>
#include <DgnPlatform\DgnECManager.h>
#include <DgnPlatform\DgnECInstance.h>
#include <DgnPlatform\DisplayRules.h>
#include <DgnPlatform\DisplayRulesManager.h>
#include <DgnPlatform\DisplayRuleActions.h>
#include <DgnPlatform\DetailingSymbol\DetailingSymbol.h>
#include <DgnPlatform\DetailingSymbol\DetailingSymbolHandlers.h>
#include <DgnPlatform\DigitalSignatureCellHeaderHandler.h>
#include <dgnplatform\TextBlock\TextBlockIterators.h>
Bruce