Following parameters are required:
1. cid (content id), sid (site ids, For example 0 for US)

Or

2. cid (content id), ver (version)

Or

3. sid (site ids, For example 0 for US), pkg (package), spkg (sub package), name, type (content type - 0:BANNER | 1:STATIC_HTML | 3:EMAIL_STATIC_CONTENT | 4:DYNAMIC_EMAIL_CONTENT | 5:FLASH | 6:MESSAGECENTER_HTML | 7:MESSAGECENTER_XSL | 8:SURVEY_FORM ...)