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--- bds [2021/07/23 04:50] – emphasise that thconfig text, lookup, layout can be in a separate input file brucemutton
+++ bds [2024/11/17 05:49] (current) – [Concepts] clarify maps off brucemutton
@@ Line 83: / Line 83: @@
 **
 ''export map -projection plan        \''\\
-''-layout LayoutMapThisCave     \''\\
+''-layout LayoutMapThisCave     \'' **# called first, processed first** \\
-''-layout LayoutMapThisCavePlan \''\\
+''-layout LayoutMapThisCavePlan \'' **# called last, processed last** \\
 ''-output ./Output/MapBulmerSystem_Plan.pdf''
 **
@@ Line 156: / Line 156: @@
 **Source**  specifies the survey data and scraps or maps that are to be compiled.  You must specify at least one source.
 \\ \\
-**maps** if maps OFF is chosen, defined map structures are NOT parsed to the outputs (therefore offsets are disabled and previews of passages are not shown).  Only scraps from the selected (or source) surveys are output.  Survey centrelines and stations are not output. Optional.
+**maps** if maps OFF is chosen, defined map structures are NOT parsed to the outputs (therefore offsets are disabled and previews of passages are not shown).  Only scraps from the selected (or source) surveys or maps are output.  Survey centrelines and stations are not output. Optional.
 \\ \\
 **maps-offset** if OFF is chosen, defined offsets are ignored, and the scraps are drawn in their true positions.   Previews are exported as usual (although previews associated with any offsets are of course not required).  Maps-offset has no meaning or effect if maps off is also chosen.  Optional.
 \\ \\
-**Select** selects particular surveys and or maps to export.  If you do not select a survey, all surveys are selected by default.  If you do not select a map, all scraps and maps are selected by default.  Optional.
+**Select** selects particular surveys and or maps to export.  If you do not select a survey, all surveys are selected by default.  If you do not select a map, all scraps are selected by default and map features such as offsets and previews are not actioned.  Optional.
 \\ \\
 **Input** enters the text of other files, as though they were typed herein.  You can use ''input'' to refer to standard ''text'', ''lookup'' or ''layout'' files, and avoid having long cumbersome thconfig files.  Optional.
@@ Line 195: / Line 195: @@
 With so many layout files it is inevitable that some parameters are changed and changed back and changed back again by the various layouts called.
-The key to understanding which setting will prevail is;
+The key to understanding which setting will prevail is knowing that;
-  * knowing that the order in which the layouts are called (by a copy statement for example) determines the order that the parameters are changed, the last one called determines the final value, and
+  * the order in which the layouts are called (by a copy statement for example) determines the order that the parameters are changed, the last one called determines the final value (but see https://github.com/therion/therion/issues/425),
-  * that the order or presence of an input statement has no effect on the order the parameters are changed.  The input statement just tells Therion in which file(s) to look for layouts.
+  * layouts called in an export statement are processed in order, the last one called determines the final value, and
+  * the order or presence of an input statement has no effect on the order the parameters are changed.  The input statement just tells Therion in which file(s) to look for layouts.
 Usually there is no problem with all this changing and changing back, but some parameters don't take kindly to it at all.  On rare occasions you will find anomalies or even strange errors because of this.  To debug for this type of problem, first comment out all the layouts, and then incrementally add layouts or individual statements back into the mix.