This page is intended to capture the ongoing study and discussion in the Ext-API project related to the BSS/OSS interaction enabled through the MEF Legato specification. This is related to the JIRA item planned in the Casablanca cycle. While it is essential to carry out a detailed study on the inter-provider interactions and overall impact on ONAP as a solution, the scope of this page will be limited to the impact on External API. Additionally, while the focus is on the MEF Legato specification, there is some good amount of work being done in many SDOs to address the scope of BSS/OSS management interactions - notably TMForum, ETSI, NGMN, ONF, IETF etc. It is worth noting the scope and outcome of these SDOs and analyze some best practices that ONAP can incorporate.  Further, the page also captures the short term and long term requirements to support Legato interaction.