In the print environment, libraries purchase and thus own books and journals. In the online environment, the acquisitions model is very different. However, if there is any break in the renewal of the online subscription, then in addition to paying for current issues, the library must purchase access to backfile content at the then-current rate. Paid journals usually require that libraries formally agree to a set of terms or conditions for use. Thus access would be limited to specific areas or departments of a campus and be unavailable from others.
Many libraries negotiate objectionable terms such as the ones listed above with journal publishers.
In some cases, alternative terms can be agreed upon. Negotiations can definitely slow down the ability of a library to provide rapid access to a journal online. These aggregators tend to offer access to a very stable set of titles. Other aggregators, such as Proquest databases like PA Research II, tend to offer a full-text database with content that fluctuates. Aggregators such as OCLC Electronic Collections that do not store content on their servers, but which serve as gateways to content held on publishers' servers.