(SDMMC) What's the point of DTEN?

[PhucXDoan]

I'm referring to RM0481 Rev 4 and I'm currently working on my SDMMC driver. For one reason and another, I need to start a data transfer for multiple read/write commands, but without sending the command again (because it has already been done so).

The RM states this about the DTEN (Data Transfer Enable) bit:

 

Ok. Maybe I'm missing something, but isn't the whole point of SDMMC is to communicate with SD, SDIO, and eMMC cards? The marketing people said so:

 

What gives? Can I use or not use the DTEN bit? Or is it just leftover legacy from older versions of the SDMMC IP?

[PhucXDoan]

I should probably also note that the description for the DTEN bit states that it shouldn't be used for SD or eMMC cards, which suggests it's meant for SDIO? Not exactly clear.