part and body in 0.17

hi,

in Version 0.17 some things seem to have conceptually changed.

When i click on a surface and want to create a sketch on that, i offen get the error-msg: „In order to use PartDesign you need an active body object in the document […]“.

Does anyone know where i can find the dokumentation on that, which explains the difference between part and body, or a good tutorial ?

Best regards,
Oliver

finally i found some info on

https://www.freecadweb.org/wiki/Release_notes_0.17

https://www.freecadweb.org/wiki/0.17:PartDesign
or
https://www.freecadweb.org/wiki/Sandbox:Part_Design_Next#Part_Design_Next

https://forum.freecadweb.org/viewtopic.php?f=9&t=15269