In Lightroom how do you specify Perceptual or Relative when exporting image?

Question

In Lightroom 6 I can use Soft Proofing to see what my image will look like with different profiles, and I can choose whether to do the conversion using Perceptual or Relative.

However when I actually export the image (i.e as jpeg) I can specify the profile to use and I assume at this point when you click Export it then makes adjustments in the images RGB values to give the best mapping from the LAB values. But you cannot specify whether to use intent perpetual or intent relative - so which one does it use ?

I found some information here https://forums.adobe.com/thread/1083949 for Lightroom 4 but Im finding the thread unclear. But it did open my eyes to the Print to JPEG option in the print tab, is using this just the same as exporting to JPEG but with additional options such as rendering intent or not. For example is it sensible to use this for creating an image to display on a website or can it only be used for creating a jpeg for eventually printing.

Answer 1

No answers so I have attempted an answer myself from what Ive learnt on discussions at. https://forums.adobe.com/thread/1083949

It seems there is not currently the option to specify Perceptual or Relative when exporting images. But furthermore perceptual or relative intents are defined within the color model itself and for the standard color models provided by Lightroom of sRGB and AdobeRGB no perceptual rendering is available so even if the option did exist it would always do relative anyway. ProPhoto model is large enough to encode (approximately) all modifications done in Lightroom anyway so rendering intent is irrelevant for this anyway.

The Print to JPEG option does allow the rendering intent to be specified and also allows CMYK based color profiles to be used, and these profiles are much more likely to support perceptual rendering then RGB based color profiles.