Can it be used as a SAAS

[ugintl]

Can it be used to make a saas app? I mean users will register and can have their own erp. Sub-domain or sub-site. Something like that.

[arnaudom]

Yes, of course; but has it is the modules will not provide the automated Saas account creation and the required installation for the customer. You will have to add a layer of code for that, a profile or install manually each account on demand.

[ugintl]

There is a concept of muti site in drupal. Do you know about it?

[arnaudom]

Yes, you can use multi-sites configuration, but you have to automate the setup of multisite, drupal install, server configuration and other settings if you want a system to run from a simple user registration.