If Web Viewer is not up or you cannot log in, find the build number in a Web Viewer File
Locate the "deployed" files.
For Apache Tomcat
<catalina_base>/webapps/CAOMWebViewer12/META-INF
For IBM WebSphere <web_sphere>/AppServer/profiles/<your_app_server>/installedApps/<your_node>/CAOMWebViewer12_ear.ear/CAOMWebViewer12.war/
Edit the MANIFEST.MF file in the directory or on USS, browse the MANIFEST.MF in ASCII Get values like... Implementation-Version: 12.1.6 Implementation-Build: 199