Updated development guide

misc/readmes/profile_developers_guide.txt

@@ -22,6 +22,13 @@ Each value can have optional "aliases", these alias
 values are encoded into the same binary value as the
 associated primary value.
 
+A profile must use expresion tag=the_first_tagvalue_alias,
+as other alliases trigger an error. 
+E.g. if there is a line in lookups.dat file
+"bicycle;0001245560 yes allowed"
+a profile must use "bicycle=yes",
+as "bicycle=allowed gives an error".
+
 The numbers in the lookup table are statistical
 information on the frequency of the values in the
 map of germany - these are just informational and
@@ -88,11 +95,11 @@ the routing engine:
 
   - variables to modify BRouter behaviour
   
-   - processUnusedTags
-         default is false. If an OSM tag is unused
-         within the profile, BRouter totallgy ignores tag existence
-         what increases BRouter speed. As sidedgjv effect, the tag is not even listed
-         in the route segment table nor the table exported as CSV.
+   - processUnusedTags  ( default is false )
+         If an OSM tag is unused within the profile, BRouter totally ignores the tag existence
+         what increases BRouter speed. As a side effect, the tag is not even listed
+         in the route segment table nor the table exported as CSV. Setting it to true/1,
+         Brouter-web Data page listed all tags present in the RD5 file.
 
 - for the way section these are
 
@@ -208,7 +215,10 @@ The initial cost classifier
 
 To trigger the addition of the "initialcost", another variable is used:
 "initialclassifier" - any change in the value of that variable leads
-to adding the value of "initialcost".
+to adding the value of "initialcost". 
+
+An useful case may be an initial cost four mounting/dismounting a bicycle, 
+having set an initialclassifier for ways without bicycle access, with high initialcost.
 For backward compatibility, if "initialclassifier"  = 0, it is replaced
 by the costfactor.
 
@@ -231,6 +241,75 @@ OR
     and some other ways have the higher Priorityclassifier value.
 
 
+The elevation buffer ( From Poutnik's glossary )
+-------------------
+with related 3 internal BRouter variables:
+    - elevationpenaltybuffer
+    - elevationmaxbuffer
+    - elevationbufferreduce
+
+the Elevation Buffer is BRouter feature to filter elevation noise along the route. 
+It may be real, or caused by the artefacts of used SRTM elevation data.
+
+From every elevation change is at the first place cut out amount 10*up/downhillcutoff
+per every km of the way length. What remains, starts to accumulate in the buffer. 
+IF cutoff demand of elevation per length is not saturated from incoming elevation, 
+it is applied on elevation remaining in the buffer as well.
+
+E.g. if the way climbs 20 m along 500 m, and uphillcutoff=3.0, then 10*3.0*0.5 = 15 m
+is taken away and only remaining 5 m accumulates. But if it climbed only 10 m
+on those 500m, all 10 m would be "swallowed" by cutoff,
+together with up to 5 m from the buffer, if there were any.
+
+When elevation does not fit the buffer of size elevationmaxbuffer, 
+it is converted by up/downhillcost ratio to Elevationcost portion of Equivalentlength. 
+Up/downhillcostfactors are used, if defined, otherwise CostFactor is used.
+
+elevationpenaltybuffer is BRouter variable, with default value 5(m).
+   The variable value is used for 2 purposes:
+   With the buffer content > elevationpenaltybuffer, it starts partially convert
+   the buffered elevation to ElevationCost by Up/downhillcost, with elevation taken 
+        = MIN (Buffer - elevationpenaltybuffer, WayLength[km] * elevationbufferreduce*10
+   The Up/downhillcost factor takes place instead of costfactor at the percentage of
+   how much is WayLength[km] * elevationbufferreduce*10 is saturated
+   by the buffer content above elevationpenaltybuffer.
+        
+elevationmaxbuffer - default 10(m) - is the size of the buffer, above which
+   all elevation is converted to Elevationcost by Up/Downhillcost ratio, 
+   and - if defined - Up/downhillcostfactor fully replaces Costfactor
+   in way cost calculation.
+    
+elevationbufferreduce - default 0(slope%)- is rate of conversion of the buffer content
+   above elevationpenaltybuffer to ElevationCost. For a way of length L, 
+   the amount of converted elevation is L[km] *elevationbufferreduce[%]*10. 
+   The elevation to Elevationcost conversion ratio is given by Up/downhillcost.
+    
+Example: 
+   Let examine steady slopes with elevationmaxbuffer=10, elevationpenaltybuffer=5, 
+   elevationbufferreduce=0.5, cutoffs=1.5, Up/downhillcosts=60
+
+   All slopes within 0 .. 1.5% are swallowed by the cutoff
+
+   For slope 1.75%, there will remain 0.25%. 
+       That saturates the elevationbufferreduce 0.5% by 50%. That gives Way cost
+       to be calculated 50% from costfactor and 50% from Up/downhillcostfactor. 
+       Additionally, 0.25% gives 2.5 m per 1km, converted to 2.5*60 = 150m of Elevationcost.
+
+   For slope 2.0%, there will remain 0.5%.
+       That saturates the elevationbufferreduce 0.5% by 100%. That gives Way cost
+       to be calculated fully from Up/downhillcostfactor. Additionally, 
+       0.5% gives 5 m per 1km, converted to 5*60 = 300m of Elevationcost. 
+       Up to slope 2.0% the buffer value stays at 5m = elevationpenaltybuffer.
+
+   For slope 2.5%, there will remain 1.0% after cutoff subtract, 
+       and 0.5% after the buffer reduce subtract. The remaining 0.5% accumulates in the buffer
+       by rate 5 m/km. When the buffer is full (elevationmaxbuffer), 
+       the elevation transforms to elevationcost by full rate of 1.0%, i.e. 10 m/km, 
+       giving elevationcost 10*60=600 m/km.
+
+
+
+
 Technical constraints
 ---------------------
 
@@ -250,8 +329,8 @@ Technical constraints
 - Ways with costfactor >= 10000 are considered as if they did not exist at all.
 
 - Ways with costfactor = 9999 are considered as 
-      if they did not exist, but only during route calculation.
-      The navigation hint generator takes them into account.
+      if they did not exist during route calculation,
+      but the navigation hint generator takes them into account.
 
 
 
@@ -264,6 +343,8 @@ or set up a local installation.
 BRouter-Web has a window at the lower left corner with a "Profile"
 and a "Data" tab. Here, you can upload profile scripts and see
 the individual cost calculations per way-section in the "Data"-tab.
+Activate eventually for the provile debugging "assign processUnusedTags = true"
+to see on the Data tab all present OSM tags, not just those used in the tested profile.
 
 
 Lookup-Table evolution and the the "major" and "minor" versions
@@ -310,5 +391,4 @@ Other resources
 ---------------
 
 See https://github.com/poutnikl/Brouter-profiles/wiki/Glossary
-as a complementary inofficial source
-about various profile internals.
+as a complementary inofficial source about various profile internals.