There are two ways to share different UDTT components and resources on a multi-project environment.
Method 1: Import the definitions into the global definition files
In this case, these components appear in the Project Explorer in the common folders and there is no difference between those that are defined in the current project or those that are defined in a different project. In the reference selection panel, when setting a value for a refId field, these components appear in the Global folder.
Method 2: Set in the btt.xml files which are the projects that are going to share their content as part of a multi-project environment
The UDTT components in these projects (self-defined transactions elements and global web resources), when being referenced, are internally identified by adding a prefix to their given Id. In some cases (remote self defined operations and flows, global operations) the prefix is also shown in the UDTT perspective, so the functional developer can easily understand that they are defined in another project and identify the project in the workspace. The prefix that identifies each of the projects is set in the btt.xml file and is configured by the technical developer. The following example shows the definition in the btt.xml file of the projects that share their components with the local project being defined and the id associated to each one of them, that is used as prefix (the project CW_CommFlowWeb uses prefix CommFlow).