I noticed on Paul Z's thread that people are talking about several different things under the one term. Here's my attempt to clarify, just a start. Please add corrections or comments. I'm certainly no expert at managing shrubs.

When pegging, remove the growth tip, if any, unless you are also tip-layering.

---Pegged (fountain)---

For adding more width and bloom to roses that naturally grow in a tall vase shape; also for roses that don't branch well when given normal shrub pruning. Bend the canes over in a low or medium arch and anchor the tips firmly near the ground. May be combined with tip-layering if you want more plants. In spring, remove strong laterals that have developed near the top of the arches, as these spoil the lines of the plant.

---Pegged (horizontal)---

For maximum ground coverage and minimum height; canes must be somewhat flexible. Stretch the cane out and fasten it to a line of pegs at a height of maybe 6". It should produce a thicket of strong vertical laterals that carry the flowers.

---Self-pegged (dome-shaped)---

Bend long whippy shoots back over the top of the plant and down; fasten to canes on the other side of the plant. This produces an inelegant cane structure which should, however, be covered by a mass of leaves and flowers on vertical laterals/sublaterals. Do the self-pegging in spring before leafing-out, or leaves will be upside down.

Cane segments bent downward may not produce breaks or blooms, but they contribute rigidity and continue to supply energy to the plant. Eventually they may die back harmlessly. Same is true of. . .

---Self-pegged (crown-shaped)---

Bend long whippy shoots out, down, and back, fastening the cane's tip to its own base. This can be a good way to start a floppy rose on the path to uprightness. It conserves plant energy as opposed to cutting the flexible canes back. Once canes have thickened up, they can be cut back to the top of the arch in spring.