From Hard Drop  Tetris Wiki
Perfect DT (Perfect Double Triple / パーフェクト DT) is a setup invented by a Japanese player named Yuu. It resembles a TKI 3 Opening but with the L placed upright on top of S which makes it looks kind of like a "wing". Usually made to achieve a TSpin Double which could then be continued with TSpin Triple without wasting a single T and usually ends with 8th row Perfect Clear. This is one of the only discovered setups that could achieve 8th row Perfect Clear without wasting a single T (other setups like Albatross Special and Pelican could only do Perfect Clear after 10 cleared lines). This setup could be made with an early I and S have to come before L. Perfect Clear after 14 lines is also possible.
First Bag
Normal Setup

Mirrored Setup

Second Bag
TSpin Triple
This setup is usually continued by TSpin Triple. Notice how JI and LO could be swapped which increases the chance to score a TSpin Triple without wasting a single T. It uses an unusual overhang but it works nonetheless.
If J comes early but Z comes before I, one could still create a TSpin Triple with Z placed vertically on top of J.
TSpin Double
If it is impossible to make a TSpin Triple on the second bag, one could still continue with a TSpin Double. The chance to stack this one is 100% because O, S and Z can be stacked in any order.
The O, S and Z pieces can be stacked in one of four ways:
It is possible to continue the TSpin Double with Type 1 ST Stacking. Here is an example:
Form 1
3 Bag Perfect Clear
If one did the normal setup, then there is a 75.87% chance to do a Perfect Clear after 8 lines.
Mirrored Setup
On the other hand, if one did the mirrored setup, then there is a 74.33% chance that it could end with 8th row Perfect Clear. The probability is lower because fewer ISpins work there.
Form 1.1
If one cannot make a Perfect Clear after 8 lines, sometimes, they can achieve a PC after 14 lines. For this form, O should come before S and T.
 96.07%: An STSD. There are two ways to stack it. Only O should come before J (first diagram only). A few solutions can make a TSpin beforehand.
If one cannot make a Perfect Clear, then they may transition to LST Stacking.
Here are some additional stacks, though not necessary to memorize.
 96.11%: There are three ways to stack and has a high probability, but cannot make a TSpin during Perfect Clear.
Below are examples of a TSpin that can be made from this form (the second example shows an STSD).
 99.13%: This one has a high probability, but has so many solutions and is a bit unsuitable for Perfect Clear. It is better to make a TSpin instead.
Below are examples of making a TSpin from this form:
Form 1.2
One is always able to stack their third bag like this; only the ZOS shape varies. However, there will be one hole clogged after the TSD.
Use the fourth bag to open the hole. Some examples (the fourth example shows forecasting):
In this form, 5bag Perfect Clear is possible, but its efficiency is too low to memorize. Below is an example of how the fourth bag might be used (93.57%):
Form 2
For this form, Perfect Clear after 8 lines is impossible, so use any of the three forms below.
Form 2.1
Use this whenever O comes early in the third bag.
 95.40%: An Imperial Cross. TSpin Double is often possible before the PC and four solutions. Only S needs to come before Z and T.