The answer is no. A snapshot can only be generated at the Delivery Unit and Application levels. 

We currently support subversion (SVN) and Team Foundation Server (TFS) through the Delivery Management Tool (DMT).

You can see specific details on how DMT interacts with Source Code Management (SCM) systems in the on-line DMT help in the section:

Package Configuration tab - Where is your source code?

as well as in the specific pages for each system:

Subversion

Techno - Team Foundation Server

You can check with CAST consulting or CAST Product Management Team in regards to the possibility of any other SCM plugins that might be available or planned at some point. 

Efiles represent source files for Web technologies (HTML, JSP, JS, ASP).

They are required in the context of Web technologies since the files can mix several technologies, so we need a parent to attach all these artifacts of different technologies.

This isn't required in analyzers such as J2EE or CPP where the files are mono-technology and we can remain at the artifact level.

  The file extensions supported by RPG pre-processor are  - "RPG", "rpg", "rpg38", "rpg38", "sqlrpg", "SQLRPG", ; "rpgle", "RPGLE", "sqlrpgle", "SQLRPGLE", ; "CLP", "clp", "CL", "cl", "clp38", "CLP38", , "cl38","CL38", "clle", "CLLE", "LF", "lf", "LF38", "lf38", ; "PF", "pf", "PF38", "pf38", ; "DSPF", "dspf" , "DSPF38", "dspf38" , ; "PRTF", "prtf", "PRTF38", "prtf38", ; "cle", "CLE", "c", "C", ; "CPYLE", "cpyle", "genle", "GENLE", ; "BND", "bnd",