Vivado always expands the dictionary mappings with set_property (set_property -dict) when saving constraints. For example, when this constraint is added to the design in the tcl console: set_property -dict {PACKAGE_PIN H10 IOSTANDARD LVCMOS18} [get_ports clk] ...
In Vivado versions prior to 2015.3, if the properties specified with -dict are only used for Implementation, this message can be ignored. If the properties are also used for Synthesis, you need to re-write the constraint to manually expand it into separate set_property commands for each name...
65248 - 2015.2 Vivado - incorrect argument "-dict" for "set_property" at line 1 of file *.xdc. Description When I use the "-dict" option with "set_property" in the XDC file, I receive the following message during Synthesis in Vivado 2015.2: Start Applying 'set_pr...