Here are the data structures with brief descriptions:

_CacheSbit
_DrawTextAttrib
_HyperAttribs
_MGContext
_point
_TextString
_VBox
DLA_struct
fpa1_syntaxItem
HttpCookieManager_t
HttpResponse_t
MHEG5Application
MHEG5Audio
MHEG5Bitmap
MHEG5BooleanVariable
MHEG5Button
MHEG5CiFileAcknowledgeEventParams_tag
MHEG5ContentVariable
MHEG5cookie_t
MHEG5DynamicLineart
MHEG5Entryfield
MHEG5FsStorageParams_tag
MHEG5Generic
MHEG5Hotspot
MHEG5Hypertext
MHEG5IntegerVariable
MHEG5Interactible
MHEG5Lineart
MHEG5MappingIter_t
MHEG5ObjectRefVariable
MHEG5OctetStringVariable
MHEG5Program_struct
MHEG5Pushbutton
MHEG5Rectangle
MHEG5ResetResolutionParams_tag
MHEG5RTGraphics
MHEG5Scene
MHEG5Slider
MHEG5StopEventParams_tag
MHEG5Stream
MHEG5Switchbutton
MHEG5Text
MHEG5TimerEventParams_tag
MHEG5TokenGroup
MHEG5TokenManager
MHEG5Video
MHEG5Visible
point_list
polygon
s_booking
s_CiStart
s_CiStop
s_content
S_CRID_DETAILS
s_crid_rec
s_datetime
s_DsmccEvent
S_DvbComponent
S_DvbLocation
S_DvbLocator
s_dvpeventtype
s_fileAck
S_FontData
s_FontMetrics
s_FontProp
S_ICSKeys
S_ICSLangInfo
S_ICSPidInfo
S_ICSPidKeys
S_ICSSubtPage
s_image
s_json_members
s_keypressevent
s_location
S_MHEG_OSD_COLOUR_MAP
S_MhegConfig
s_mhg_message
S_PVR_DATE
S_PVR_TIME
s_ratio
S_RECTANGLE
s_StartDsmApp
s_StreamEvent
s_StreamPids
S_STRING
s_surface
scounterTrigger
sFontDetails
sFontSize
sMH5GroupRef
sMHEG5Action
sMHEG5ActionList
sMHEG5ContentBody
sMHEG5CursorShape
sMHEG5DisplayStackItem
sMHEG5Font
sMHEG5FontBody
sMHEG5GList
sMHEG5Group
sMHEG5HttpStreamRequest
sMHEG5Ingredient
sMHEG5IntList
SMHEG5IntPair
sMHEG5ItemList
sMHEG5Link
sMHEG5ListGroup
sMHEG5MovementTable
sMHEG5ObjectReference
sMHEG5Palette
sMHEG5PosList
sMHEG5QueueItem
sMHEG5Root
sMHEG5String
sMHEG5TokenSlot
sParamList
sRegion
synItemData
U64BIT
U_PARAM
VRect