This code system http://terminology.hl7.org/CodeSystem/security-source-type defines the following codes:

Code Display Definition
1 User Device End-user display device, diagnostic device.
2 Data Interface Data acquisition device or instrument.
3 Web Server Web Server process or thread.
4 Application Server Application Server process or thread.
5 Database Server Database Server process or thread.
6 Security Server Security server, e.g. a domain controller.
7 Network Device ISO level 1-3 network component.
8 Network Router ISO level 4-6 operating software.
9 Other Other kind of device (defined by DICOM, but some other code/system can be used).
<status value="active"/> <experimental value="false"/> <date value="2010-08-26T00:00:00+10:00"/> <publisher value="Security"/> <contact> <name value="Security"/> <telecom> <system value="url"/> <value value="http://www.hl7.org/Special/committees/secure"/> </telecom> </contact> <description value="The type of process where the audit event originated from."/> <jurisdiction> <coding> <system value="http://unstats.un.org/unsd/methods/m49/m49.htm"/> <code value="001"/> <display value="World"/> </coding> </jurisdiction> <caseSensitive value="true"/> <content value="complete"/> <concept> <code value="1"/> <display value="User Device"/> <definition value="End-user display device, diagnostic device."/> </concept> <concept> <code value="2"/> <display value="Data Interface"/> <definition value="Data acquisition device or instrument."/> </concept> <concept> <code value="3"/> <display value="Web Server"/> <definition value="Web Server process or thread."/> </concept> <concept> <code value="4"/> <display value="Application Server"/> <definition value="Application Server process or thread."/> </concept> <concept> <code value="5"/> <display value="Database Server"/> <definition value="Database Server process or thread."/> </concept> <concept> <code value="6"/> <display value="Security Server"/> <definition value="Security server, e.g. a domain controller."/> </concept> <concept> <code value="7"/> <display value="Network Device"/> <definition value="ISO level 1-3 network component."/> </concept> <concept> <code value="8"/> <display value="Network Router"/> <definition value="ISO level 4-6 operating software."/> </concept> <concept> <code value="9"/> <display value="Other"/> <definition value="Other kind of device (defined by DICOM, but some other code/system can be used)."/> </concept> </CodeSystem>