public enum INSTALLSTATE
{
    INSTALLSTATE_NOTUSED      = -7,  // component disabled
    INSTALLSTATE_BADCONFIG    = -6,  // configuration data corrupt
    INSTALLSTATE_INCOMPLETE   = -5,  // installation suspended or in progress
    INSTALLSTATE_SOURCEABSENT = -4,  // run from source, source is unavailable
    INSTALLSTATE_MOREDATA     = -3,  // return buffer overflow
    INSTALLSTATE_INVALIDARG   = -2,  // invalid function argument
    INSTALLSTATE_UNKNOWN      = -1,  // unrecognized product or feature
    INSTALLSTATE_BROKEN       =  0,  // broken
    INSTALLSTATE_ADVERTISED   =  1,  // advertised feature
    INSTALLSTATE_REMOVED      =  1,  // component being removed (action state, not settable)
    INSTALLSTATE_ABSENT       =  2,  // uninstalled (or action state absent but clients remain)
    INSTALLSTATE_LOCAL    =  3,  // installed on local drive
    INSTALLSTATE_SOURCE       =  4,  // run from source, CD or net
    INSTALLSTATE_DEFAULT      =  5,  // use default, local or source
}

VB Definition:

Public Enum INSTALLSTATE
    ''' <summary>
    ''' Component disabled.
    ''' </summary>
    NOTUSED = -7
    ''' <summary>
    ''' Configuration data corrupt.
    ''' </summary>
    BADCONFIG = -6
    ''' <summary>
    ''' Installation suspended or in progress.
    ''' </summary>
    INCOMPLETE = -5
    ''' <summary>
    ''' Run from source, source is unavailable.
    ''' </summary>
    SOURCEABSENT = -4
    ''' <summary>
    ''' Return buffer overflow.
    ''' </summary>
    MOREDATA = -3
    ''' <summary>
    ''' Invalid function argument.
    ''' </summary>
    INVALIDARG = -2
    ''' <summary>
    ''' Unrecognized product or feature.
    ''' </summary>
    UNKNOWN = -1
    ''' <summary>
    ''' Broken.
    ''' </summary>
    BROKEN = 0
    ''' <summary>
    ''' Advertised feature.
    ''' </summary>
    ADVERTISED = 1
    ''' <summary>
    ''' Component being removed (action state, not settable).
    ''' </summary>
    REMOVED = 1
    ''' <summary>
    ''' Uninstalled (or action state absent but clients remain).
    ''' </summary>
    ABSENT = 2
    ''' <summary>
    ''' Installed on local drive.
    ''' </summary>
    LOCAL = 3
    ''' <summary>
    ''' Run from source, CD or net.
    ''' </summary>
    SOURCE = 4
    ''' <summary>
    ''' use default, local or source
    ''' </summary>
    [DEFAULT] = 5
End Enum