Deformation specification not defined in print

Hi
Attached part is a weld part. critical dimension .900+0/-.001 inch with in spec measured by mirco meter or CMM(single side plane to 6 random points).
but if measured a co-plane (two side planes) this plane flatness is .005-.006inch.
or measured both side .900 center line not a strightness line.
Does any ISO specification which define a general flatness or straightness.
Or we need to ask R&D add flatness or straightness spec on print?

If flatness is critical for the proper function of this part, it must be specified.
Both GD&T Standards ASME Y14.5-2009 and ISO 1101 provide requirements for flatness and straightness. Clarify with your engineering folks and/or your customer.