The documentation (http://docs.alfresco.com/5.0/pra/1/concepts/cmis-1.1-browser-binding.html) does not cover if one can update an existing document (metadata and content) using CMIS 1.1 browser binding. It does say "You use the HTTP POST command to create, update, and delete content from a repository." but does not provide an example. I wonder if anyone has done that and what parameters (cmisaction, objectid etc) are needed. Thank you.
In case anyone is interested, I figured it out with the help from Alfresco support. You can set cmisaction to update/checkOut/checkIn etc to update/check out/check in document with CMIS 1.1 browser binding. A nice trick is to do these operations in CMIS Workbench and monitor the HTTP traffic in a tool like Charles Proxy.