TIER 2 visa documents - English language ability

[resumeforc]

Hello ,
Thank you all for all the good information that we can get via this forum .
I have few questions about the document required for English language ability ? What is the acceptable document ?
I have heard of NARIC certificate but when I visited their site ,I found following 2 certificates that can be sought . Which one or both are required for TIER II general ?
Statement of Comparability.
English Language Assessment
Also ,if someone can also clear a doubt as to what documents are required to get the NARIC certificates ,it would be useful .
The website says transcripts and a letter from the institution where you studied, confirming that your qualification was taught in English .
Does transcript mean marksheets issued by university ?
Also does anyone have idea about how to get the second one - medium of instruction for Mumbai university ?Is it possible to get it online ?
Thanks in advance for all the help.