SharePoint Feature Description
In our test implementation of Microsoft SharePoint Server, there are certain lists with large amount of data, so these views are the efficient way to work with these huge lists.
Views have some features to filter the data. For example it is possible to see all of the correspondences in a project by filtering the project column in the correspondence list. Because this filter may apply to different projects and the user wants to freely switch between different projects, it is not efficient to create a separate view for each project and predetermine the filtering option. The way the user use this feature is to create a general view in the correspondence list and filtering data by hovering the mouse on the project lookup column and select the required project.
SharePoint Challenge Description
It is not possible in the standard view to filter all the correspondences of two projects at the same time. You can only filter projects one at a time. So it is kind of hard for the user to find cross project information.
One solution may be to suggest to create data views in Microsoft SharePoint Designer and apply custom filtering to show data, but end user has no access to this tool and it is beyond the skill set of the end users.
There is no out-of-the-box solution to this SharePoint limitation. The user should do extra work to create separate views for each cross project information and use them according his requirements.