minor help updates (extra peaks; set one value/table)

Author: briantoby

MDhelp/docs/powderinst.md

@@ -31,9 +31,10 @@ A single menu is provided with the selection of instrument parameters.
 
 * **Copy flags**: this copies the instrument parameter refinement flags shown to other selected powder patterns. If used, a dialog box (Copy refinement flags) will appear showing the list of available powder patterns, you can copy the instrument parameter refinement flags to any or all of them; select 'All' to copy them to all patterns. Then select 'OK' to do the copy; 'Cancel' to cancel the operation. The copy will only work for instrument parameters that are commensurate with the one that is shown, e.g. single radiation patterns will not be updated from Kα1α2 ones.
 
-* **Set one value**: this is used to set a single selected instrument parameter for a selected set of PWDR histograms. The same value can be used for all histograms, or a dialog can be used to provide a table where you can set the values differently for each of selected histograms.
+* **Set one value**: this is used to set a single selected instrument parameter for the current selected PWDR histogram. Once changed, the new value can be copied to selected other histograms. There is also an "Edit in table" option. When that is used, the value can be set individually (likewise for the refine flag) for every selected histogram. Note that the "down arrow" button in the table is used to copy the selected value to all
+histograms below. 
 
-* **Show multiple**: Displays instrument parameters for all histograms similar to the current selected histogram in a dingle table.
+* **Show multiple**: Displays instrument parameters for all histograms similar to the current selected histogram in a single table.
 
 Note that you can change any of the instrument coefficients and the instrument peak widths plot will be updated to show the effect of the change on overall peak widths. 
 Note that while the software does allow you to refine any of the instrument coefficients, refinement of these terms is discouraged, except for generating instrumental profiles for calibration. NB: In certain circumstances some refinement choices are ignored: e.g. Zero is not refined (or used) during peak fitting. Also, some parameter choices may lead to unstable refinement, e.g. combining refinement of Lam (wavelength) and lattice parameter. In Rietveld fitting, examine the 'Covariance' display for highly correlated parameters.

MDhelp/docs/powderpeaks.md

@@ -68,3 +68,8 @@ For all actions involving mouse clicks such as those below, be sure that the Zoo
 * You can move a Peak List item using the mouse on the plot by: position the pointer on the blue line for the peak you wish to move and then hold the left mouse button down, dragging the line to the desired position. When the mouse button is released, the peak line will be drawn in the new position.
 * The fit limits can be changed from the plot either here or in the Limits data tree. Change the upper and lower Tmin/Tmax values by clicking on the appropriate vertical line and dragging it to the right or left.
 * Highlight each peak in the list successively using the "d" keyboard key to move down the list or "u" to move up the list. 
+
+
+### "**Extra Peak**" Mode
+
+When working with full-pattern fits, it is sometimes useful to pay attention only to the peaks that are not being indexed and fit by the full pattern fit. One reason for this may be to learn more about a phase that is not currently being fit or with magnetic scattering, one may have fit the chemical ("nuclear") structure and one needs to identify the additional peaks that are seen below a magnetic phase transition in order to understand the lowered symmetry of the magnetic lattice, or similarly to explore lowering of symmetry as a phase transitions to the symmetry of a subgroup, perhaps as the temperaure is lower or as ions order due to a compositional change. In "Extra Peak mode", individual peak fitting is performed not on the diffraction data, but rather on the difference between the observed pattern and that computed from the full pattern fitting. A separate peak list is kept for these "extra peaks". This "Extra Peak Mode" can be entered either from pressing the button labeled "Switch to In "Extra Peak mode", or by using the checkmark menu button in the "Peak Fitting" menu labeled "Add impurity/subgrp/magnetic peaks."