6 Appendix A: Product Behavior

The information in this specification is applicable to the following Microsoft products or supplemental software. References to product versions include updates to those products.

• Windows Vista operating system

• Windows Server 2008 operating system

• Windows 7 operating system

• Windows Server 2008 R2 operating system

• Windows 8 operating system

• Windows Server 2012 operating system

• Windows 8.1 operating system

• Windows Server 2012 R2 operating system

• Windows 10 operating system

• Windows Server 2016 operating system

• Windows Server operating system

• Windows Server 2019 operating system

• Windows Server 2022 operating system

• Windows 11 operating system

• Windows Server 2025 operating system

Exceptions, if any, are noted in this section. If an update version, service pack or Knowledge Base (KB) number appears with a product name, the behavior changed in that update. The new behavior also applies to subsequent updates unless otherwise specified. If a product edition appears with the product version, behavior is different in that product edition.

Unless otherwise specified, any statement of optional behavior in this specification that is prescribed using the terms "SHOULD" or "SHOULD NOT" implies product behavior in accordance with the SHOULD or SHOULD NOT prescription. Unless otherwise specified, the term "MAY" implies that the product does not follow the prescription.

<1> Section 2.2.3.2: Windows sets the application identifier to the application's system process ID.

<2> Section 2.2.3.2: In the Windows implementation, the process name is used as the name for an application.

<3> Section 2.2.3.4: In the Windows implementation, the window handle value, which uniquely identifies a window within the Windows operating system, is used as the WndId.

<4> Section 2.2.3.4: In the Windows implementation, the window title is used as the window name.

<5> Section 2.2.3.7:  In Windows implementations, the sharing manager does not send the Window Region Update PDU (OD_WND_REGION_UPDATE).

<6> Section 2.2.4.1: In Windows implementations, the GroupId field is set to 0 by the sharing manager.

<7> Section 3.1.5.1: In Windows implementations, PDUs that have an unknown type in the order header are ignored by the receivers.

<8> Section 3.1.5.1: Windows implementations disconnect the client whenever the header length field is not consistent with the length required for a particular message or with the length of the buffer received from the lower-layer protocol.

<9> Section 3.2.5.1.1: In Windows implementations, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data that it is able to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is large enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

<10> Section 3.2.5.1.1: In Windows implementations, the Name field is optional. If the Name field is not sent then the connection is not terminated.

<11> Section 3.2.5.1.2: In Windows implementations, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data that it is able to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is large enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

<12> Section 3.2.5.1.3: In Windows implementation, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data that it is able to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is large enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

<13> Section 3.2.5.1.3: In Windows implementations, all the window and application data stored by the receiver is removed when a Filter-Updated PDU is received, as the sharing manager is about to send an updated list.

<14> Section 3.2.5.1.4: In Windows implementations, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data that it is able to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is large enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

<15> Section 3.2.5.1.5: In Windows implementations, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data that it is able to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is big enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

<16> Section 3.2.5.1.6:  In Windows implementations, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data that it is able to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is large enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

<17> Section 3.2.5.2.1: In Windows implementations, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data that it is able to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is large enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

<18> Section 3.2.5.2.1: When a client is connected and authenticated, the server tries to inform the client which participant in the list corresponds to the client itself. This communication is done by sending a Participant-Created PDU to only that client but with the IS_PARTICIPANT set to 1. The client verifies the presence of the flag and remembers the ParticipantId as corresponding to itself.

<19> Section 3.2.5.2.1: In Windows implementations, the GroupId field is not interpreted by the participant.

<20> Section 3.2.5.2.2: In Windows implementations, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data that it is able to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is large enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

<21> Section 3.2.5.2.2: Windows does not parse the DiscType and DiscCode fields.

<22> Section 3.2.5.2.3:  In Windows implementations, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data that it is able to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is large enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

<23> Section 3.2.5.3.1: In Windows implementations, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data the receiver knows how to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is large enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

<24> Section 3.2.5.3.2: In Windows implementations, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data that it is able to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is large enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

<25> Section 3.3.5.1.1: In Windows implementations, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data that it is able to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is large enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

<26> Section 3.3.5.1.1: In Windows implementations, the server keeps all the windows of interest in a list. When the client requests that a window be displayed, the server checks if the window is in the list. If the window is in the list, the server attempts to show the window. Otherwise, the message is ignored.

<27> Section 3.3.5.1.1: In Windows implementations, the server verifies that the client sending the message has the right to interact with the desktop before showing the window. If the client does not have the right to interact with the desktop, the message is ignored.

<28> Section 3.3.5.2.1: In Windows implementations, a Participant-Created PDU (OD_PARTICIPANT_CREATED) is not sent by the participant.

<29> Section 3.3.5.2.2: In Windows implementations, a Participant-Removed PDU (OD_PARTICIPANT_REMOVED) is neither sent by the participant nor interpreted by the sharing manager.

<30> Section 3.3.5.2.3: In Windows implementation, if more data is received for a message than the receiver can parse, the receiver parses only the portion of the data that it is able to parse and ignores the rest. For every type of message, the size of the received data is verified to make sure that the message is large enough to contain all the fields for that particular message. If this is not the case, the connection is terminated.

Also in Windows implementations, a value of ALLOW_CONTROL_REQUEST in the Flags field is not sent by the participant and not interpreted by the sharing manager.