The matter of heading in the US has been covered by others...Runway Heading means to maintain the magnetic(except in polar areas where True is used) heading which corresponds to the magnetic bearing of the runway. TERPS provides for situations where drift would create an obstacle clearance or other problem(primary/secondary OCA areas) and in critical situations the departure procedure would not specify heading
but direct(or via a navaid derived course) to a fix.
The confusion on this point is scary...maybe the solution would be
"maintain heading (the runway bearing)" instead of "maintain runway heading".