C# Definition:

public enum ACE_TYPE : byte
{
    /// <summary>Access-allowed ACE that uses the ACCESS_ALLOWED_ACE structure.</summary>
    ACCESS_ALLOWED = 0x0,
    /// <summary>Access-allowed callback ACE that uses the ACCESS_ALLOWED_CALLBACK_ACE structure.</summary>
    ACCESS_ALLOWED_CALLBACK = 0x9,
    /// <summary>Object-specific access-allowed callback ACE that uses the ACCESS_ALLOWED_CALLBACK_OBJECT_ACE structure.</summary>
    ACCESS_ALLOWED_CALLBACK_OBJECT = 0xB,
    /// <summary>Reserved.</summary>
    ACCESS_ALLOWED_COMPOUND = 0x4,
    /// <summary>Object-specific access-allowed ACE that uses the ACCESS_ALLOWED_OBJECT_ACE structure.</summary>
    ACCESS_ALLOWED_OBJECT = 0x5,

    /// <summary>Access-denied ACE that uses the ACCESS_DENIED_ACE structure.</summary>
    ACCESS_DENIED = 0x1,
    /// <summary>Access-denied callback ACE that uses the ACCESS_DENIED_CALLBACK_ACE structure.</summary>
    ACCESS_DENIED_CALLBACK = 0xA,
    /// <summary>Object-specific access-denied callback ACE that uses the ACCESS_DENIED_CALLBACK_OBJECT_ACE structure.</summary>
    ACCESS_DENIED_CALLBACK_OBJECT = 0xC,
    /// <summary>Object-specific access-denied ACE that uses the ACCESS_DENIED_OBJECT_ACE structure.</summary>
    ACCESS_DENIED_OBJECT = 0x6,

    /// <summary>Reserved for future use. System-alarm ACE that uses the SYSTEM_ALARM_ACE structure.</summary>
    SYSTEM_ALARM = 0x3,
    /// <summary>Reserved for future use. System-alarm callback ACE that uses the SYSTEM_ALARM_CALLBACK_ACE structure.</summary>
    SYSTEM_ALARM_CALLBACK = 0xE,
    /// <summary>Reserved for future use. Object-specific system-alarm callback ACE that uses the SYSTEM_ALARM_CALLBACK_OBJECT_ACE structure.</summary>
    SYSTEM_ALARM_CALLBACK_OBJECT = 0x10,
    /// <summary>Reserved for future use. Object-specific system-alarm ACE that uses the SYSTEM_ALARM_OBJECT_ACE structure.</summary>
    SYSTEM_ALARM_OBJECT = 0x8,

    /// <summary>System-audit ACE that uses the SYSTEM_AUDIT_ACE structure.</summary>
    SYSTEM_AUDIT = 0x2,
    /// <summary>System-audit callback ACE that uses the SYSTEM_AUDIT_CALLBACK_ACE structure.</summary>
    SYSTEM_AUDIT_CALLBACK = 0xD,
    /// <summary>Object-specific system-audit callback ACE that uses the SYSTEM_AUDIT_CALLBACK_OBJECT_ACE structure.</summary>
    SYSTEM_AUDIT_CALLBACK_OBJECT = 0xF,
    /// <summary>Object-specific system-audit ACE that uses the SYSTEM_AUDIT_OBJECT_ACE structure.</summary>
    SYSTEM_AUDIT_OBJECT = 0x7,

    /// <summary>Mandatory label ACE that uses the SYSTEM_MANDATORY_LABEL_ACE structure.</summary>
    SYSTEM_MANDATORY_LABEL = 0x11
}

C# Alternative Definition:

public enum ACE_TYPE : byte
{
    Allow = 0,
    Deny = 1,
    Audit = 2
}

VB Definition:

Public Enum ACE_TYPE As Byte
    ''' <summary>Access-allowed ACE that uses the ACCESS_ALLOWED_ACE structure.</summary>
    ACCESS_ALLOWED = &H0
    ''' <summary>Access-allowed callback ACE that uses the ACCESS_ALLOWED_CALLBACK_ACE structure.</summary>
    ACCESS_ALLOWED_CALLBACK = &H9
    ''' <summary>Object-specific access-allowed callback ACE that uses the ACCESS_ALLOWED_CALLBACK_OBJECT_ACE structure.</summary>
    ACCESS_ALLOWED_CALLBACK_OBJECT = &HB
    ''' <summary>Reserved.</summary>
    ACCESS_ALLOWED_COMPOUND = &H4
    ''' <summary>Object-specific access-allowed ACE that uses the ACCESS_ALLOWED_OBJECT_ACE structure.</summary>
    ACCESS_ALLOWED_OBJECT = &H5

    ''' <summary>Access-denied ACE that uses the ACCESS_DENIED_ACE structure.</summary>
    ACCESS_DENIED = &H1
    ''' <summary>Access-denied callback ACE that uses the ACCESS_DENIED_CALLBACK_ACE structure.</summary>
    ACCESS_DENIED_CALLBACK = &HA
    ''' <summary>Object-specific access-denied callback ACE that uses the ACCESS_DENIED_CALLBACK_OBJECT_ACE structure.</summary>
    ACCESS_DENIED_CALLBACK_OBJECT = &HC
    ''' <summary>Object-specific access-denied ACE that uses the ACCESS_DENIED_OBJECT_ACE structure.</summary>
    ACCESS_DENIED_OBJECT = &H6

    ''' <summary>Reserved for future use. System-alarm ACE that uses the SYSTEM_ALARM_ACE structure.</summary>
    SYSTEM_ALARM = &H3
    ''' <summary>Reserved for future use. System-alarm callback ACE that uses the SYSTEM_ALARM_CALLBACK_ACE structure.</summary>
    SYSTEM_ALARM_CALLBACK = &HE
    ''' <summary>Reserved for future use. Object-specific system-alarm callback ACE that uses the SYSTEM_ALARM_CALLBACK_OBJECT_ACE structure.</summary>
    SYSTEM_ALARM_CALLBACK_OBJECT = &H10
    ''' <summary>Reserved for future use. Object-specific system-alarm ACE that uses the SYSTEM_ALARM_OBJECT_ACE structure.</summary>
    SYSTEM_ALARM_OBJECT = &H8

    ''' <summary>System-audit ACE that uses the SYSTEM_AUDIT_ACE structure.</summary>
    SYSTEM_AUDIT = &H2
    ''' <summary>System-audit callback ACE that uses the SYSTEM_AUDIT_CALLBACK_ACE structure.</summary>
    SYSTEM_AUDIT_CALLBACK = &HD
    ''' <summary>Object-specific system-audit callback ACE that uses the SYSTEM_AUDIT_CALLBACK_OBJECT_ACE structure.</summary>
    SYSTEM_AUDIT_CALLBACK_OBJECT = &HF
    ''' <summary>Object-specific system-audit ACE that uses the SYSTEM_AUDIT_OBJECT_ACE structure.</summary>
    SYSTEM_AUDIT_OBJECT = &H7

    ''' <summary>Mandatory label ACE that uses the SYSTEM_MANDATORY_LABEL_ACE structure.</summary>
    SYSTEM_MANDATORY_LABEL = &H11
End Enum

VB Alternative Definition:

Public Enum ACE_TYPE As Byte
    Allow = 0,
    Deny = 1,
    Audit = 2
End Enum

Notes:

More information can be found on the MSDN. The values for the enumeration come from the WinNT header file.