This script will create page layouts with a predefined number of systems per page, by setting the page break attribute to the measure that should break a page. (Finale will only break a page if the measure with the page break attribute appears first on a system.)

First, the script provides a user input dialog with 3 options:

• Number of systems per page
• Start page
• Max number of pages that should be processed

Please note the syntax for using a static member function in JW Lua, in this case UpdateFullLayout() in the FCStaffSystems class, which can be called using the syntax: finale.FCStaffSystems.UpdateFullLayout().

systemsperpage.lua

function plugindef()
   -- This function and the 'finaleplugin' namespace
   -- are both reserved for the plug-in definition.
   finaleplugin.Author = "Jari Williamsson"
   finaleplugin.CategoryTags = "Layout, Page, System, UI"
   return "Locked Systems Per Page", "Locked Systems Per Page",
           "Creates a predefined number of systems per page (by inserting page breaks)."
end
 
-- Show user dialog box
local dialog = finenv.UserValueInput()
dialog.Title = "Systems Per Page"
dialog:SetTypes("Number", "Number", "Number")
dialog:SetDescriptions("Number of systems per page:", "Start at page:", "Do it for max no of pages:")
dialog:SetInitValues(6, 1, 999)
local returnvalues = dialog:Execute()
if not returnvalues then return end
 
local systemsperpage = returnvalues[1]
local currentprocesspage = returnvalues[2]
local maxnoofprocesspages = returnvalues[3]
 
if (systemsperpage < 1) then
    print ("Input error: Invalid number of systems per page.")
    return 
end
 
if currentprocesspage < 1 then
    print ("Input error: Invalid start page number.")
    return 
end
 
local pages = finale.FCPages()
local pageprocesscounter = 0
 
while true do    
    -- Reload the page layout every time, since the layout contents changes
    finale.FCStaffSystems.UpdateFullLayout()
    if pageprocesscounter > maxnoofprocesspages then break end
    pages:LoadAll()
    if pages.Count < currentprocesspage  then break end
 
    -- Create the local-scope variables before any goto:s
    local system = finale.FCStaffSystem()
    local measure = finale.FCMeasure()    
 
    -- Get the page layout to process
    page = pages:GetItemAt(currentprocesspage - 1)
    local firstsysnumber = page:GetFirstSystem()
    local lastsysnumber = page:CalcLastSystem()
 
    -- Skip pages with no system layout, such as empty pages    
    if firstsysnumber < 1 then goto continue end    
    if lastsysnumber < 1 then goto continue end
 
    -- Check if the page contains enough systems to split the contents
    if  (lastsysnumber - firstsysnumber + 1) < systemsperpage then
        print ("Can't continue. Page", page:GetItemNo(), "contains less than", systemsperpage, "systems.")
        return
    end
 
    -- Load the system where the break should appear    
    system:Load(firstsysnumber + systemsperpage)
    if (system.FirstMeasure < 1) then goto continue end
    -- Change the measure attribute of the first measure to a page break    
    measure:Load(system.FirstMeasure)
    measure.PageBreak = true
    measure:Save()
 
    -- Process the next page
    :: continue ::
    currentprocesspage = currentprocesspage + 1
    pageprocesscounter = pageprocesscounter + 1    
end

This script creates a tacet for the selected region, regardless of if the section contains music or how the measures has been configured regarding multimeasure breaks. It requires that the Automatic Update for multimeasure rests is OFF for the file. Before the tacet , a user alert is displayed. The script also requires a selected region (JW Lua will automatically tell the user if a region isn't selected).

Specifying the multimeasure rest preference record 1 doesn't really matter here (any value would load the same preference data), but generally speaking for single-instance preference records, it's good practice to load preference record 1 anyway.

createtacet.lua

function plugindef()
   -- This function and the 'finaleplugin' namespace
   -- are both reserved for the plug-in definition.
   finaleplugin.RequireSelection = true
   finaleplugin.CategoryTags = "Layout, Measure, Rest"
   return "Create Tacet", "Create Tacet", "Creates a full tacet 'measure' for the selected region."
end
 
-- Load the multimeasure rest prefs
local mmrestprefs = finale.FCMultiMeasureRestPrefs()
mmrestprefs:Load(1)
 
-- Will not continue if auto-update of mm rests is ON
if mmrestprefs.AutoUpdate then
    print ("Automatic Update is ON in the multimeasure preferences.")
    return
end
 
local ui = finenv.UI()
if ui:AlertYesNo("Do you want to create a tacet section in this part? All music in the region will be hidden.", 
            "Are you sure?") ~= finale.YESRETURN then
    return
end
 
local region = finenv.Region()
 
-- Delete all old mm rests from the region
-- (In this case, it's safe to delete from the start, since no relocation of data records takes place.)
local mmrests = finale.FCMultiMeasureRests()
mmrests:LoadAll()
for mm in each (mmrests) do
    if region:IsMeasureIncluded(mm.StartMeasure) or region:IsMeasureIncluded(mm.EndMeasure) then        
        mm:DeleteData()
    end
end
 
local mm = finale.FCMultiMeasureRest()
mm.StartMeasure = region.StartMeasure
mm.EndMeasure = region.EndMeasure
-- Copy from the default MM rest definition
mm.NumberHorizontalAdjust = mmrestprefs.NumberHorizontalAdjust
mm.NumberVerticalAdjust = mmrestprefs.NumberVerticalAdjust
mm.ShapeEndAdjust = mmrestprefs.ShapeEndAdjust
mm.ShapeID = mmrestprefs.ShapeID
mm.ShapeStartAdjust = mmrestprefs.ShapeStartAdjust
mm.StartNumberingAt = 20000 -- A really high value here to hide the number
mm.SymbolSpace = mmrestprefs.SymbolSpace
mm.UseSymbols = mmrestprefs.UseSymbols
mm.UseSymbolsLessThan = mmrestprefs.UseSymbolsLessThan
mm.Width = mmrestprefs.Width
mm:Save()