Anchor Control arrow or point used to limit the effects of changes.
Brightness see H and L.
Control Arrow double headed arrow in the histogram showing the before and after values of the transform.
Control Point As control arrow, but a point representation, either in the curves display or another transform such as color correction.
H Hue (or colour)
HSL Colour space defined in terms of Hue, Saturation and Lightness see page 159/160 of PWP v4 manual
HSV Colour space defined in terms of Hue, Saturation and Value (brightness) see page 159/160 of PWP v4 manual
Inversion taking a range of tones or hues and making the highest values the lowest, and the lowest the highest.
L Lightness see page 159/160 of PWP v4 manual
Monochrome Containing only shades of black, grey and white an image without colour.
Sabattier Effect Effect where exposure of a partially developed image to light causes highlights to darken, resulting in a part negative, part positive image.
Single colour image an image which is mostly or completely made from a single colour, but not black and white.
Solarisation - Effect where overexposure of an image causes highlights to go black.
Stretch (the) expanding the range of a limited tonal or colour range of an image to cause deliberate posterisation and in colour a rainbow effect.
Transform object manipulation that can be selected from the transform drop don menu in PWP
Transition point. A point in an image manipulation where the effect changes from an inversion to a normal (possibly stretched) representation.
V Value or brightness of an image, see page 159/160 of PWP v4 manual
A good way of saving storage space is to save the final version of the curve, along with a thumbnail or web sized version of the result. Then only the original needs to be large, the smaller samples are really only needed for later image selection, PWP will rebuild the image quickly when it is required for printing or other uses. Be sure to save the correct curve with a descriptive name that identifies the original image and the output image. In a similar fashion, save intermediate versions by saving the curve, not an image.
This article very technical and scholarly, but very thorough and includes a good history with interesting examples of what was achievable with chemical processes:
You can find others by googling for Solarisation and Sabattier Effect.