All the statements are correct.

Since the steam is admitted from outside the steam chest, therefore, D-slide valve is also known as outside admission valve.

The throw of the eccentric is equal to half of the valve travel.

Steam lap is the distance by which the outer edge of the D-slide valve overlaps the steam port.

Valve travel is the distance moved by the valve from one end to the other end.

In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve is by increasing the angle of advance of the eccentric while the throw of the eccentric, steam lap and exhaust lap are kept constant. The method will reduce length of effective stroke of piston.

In actual practise, the displacement of the D-slide valve is greater than the steam lap by a distance known as lead of the valve.

Steam lap or exhaust lap is the distance by which the outer edge of the D-slide valve overlaps the steam port.

In actual practise, the displacement of the D-slide valve is greater than the steam lap by a distance known as lead of the valve.

Since the steam enters from the inside of the two pistons, therefore, the piston valve is also known as inside admission valve.