constraints.txt

-c https://dist.plone.org/release/6.0.0b3/constraints.txt

# Here contstraints can be added. constraints of packages included in https://dist.plone.org/release/6.0.0a4/constraints.txt cannot be modified. Here does mxdev it's purpose:
# mx.ini, the configuration file of mxdev allows to, for example, force an increased version of a core package like plone.restapi.