It is a custom bootloader,
It will allow you to flash to any type of the custom rom.

All information for you need please visit this thread.

??? im already hspl'd, is there something else on there im missing?

Please recheck the SPL in the Tri-Color screen,
Some of update via Zune will override your SPL so you need to re-flash your HSPL again.

If the bootloader is H/RSPL, the RUU will pass the model checking.
(If not, try to revert back OSPL and re-flash HSPL again.)

OK so here is a good question i have the leaked football ROM (mango) on my hd7 now when t mobile releases mango can i flash your ROM then update to mango from zune and then i will have a unlocked mango phone

You can flash my rom into the TMOUS HD7 device,
but the main system package is O2.

So you can update to mango after O2 release the update.
(anyway you can change or debrand the operator of your phone but I not recommend.)

And sure, after update your will have an unlocked mango phone by use the connection setup (and can use everytime if you got the re-lock).

yeah its still not working i dont know why i really want to try your rom

Umm... this is interesting.

Can you tell me what the device do you have HD7 or TMOUS HD7 ?

and the security unlock enable ?
(you can check this in the tri-color screen)

and try to test this rom [ROM]RUU_Schubert_O2_UK_3.04.206.01_Radio_5.66.09.21a_2 2.48.50.21_Signed
because the Model ID of both are same.

I'm on tmobile so I'm guessing i have a tmous hd7, and i didn't see anything about a security being on when i went to the try colored screen.

Okay I get it,

Your os is tmous and i guess we have the difference Model ID (MID).
By general, HD7 has the MID PD2910000 and the tmous HD7 has PD2911000.

So you need do flash via goldcard for move from current MID to general HD7,
because the HSPL can't help you to flash the other type of the MID (but help you to flash to the other type of Vendor ID).

This is only way right now, sorry about that.

My device is tmous too but i done a goldcard for a long time,
so I'll able to flash any type of rom for HD7 (O2, Telstra, Global etc..) without the problem.

I will def flash this rom once, official mango comes out, I am currently on the RTM version. But I doubt it that i will recieve the official one if I stay RTM.