Update Processors.md

Processors.md

@@ -296,3 +296,27 @@ The *TaskGroup* entity encapsulates a given set of *Task* entities and provides
 **Task** (1 -n)
  
  
+## Built-in variables ##
+  
+Inside a *Processor* definition configuration file some build-in parameter can be used to abstract some configurations: 
+
+The build-in parameters are replaced at runtime in all <Parameter> and in all custom tags (eg. <MyCustomTag>*$DAY*</MyCustomTag>)
+
+  
+*$BASEPATH* The base path variable configured in *DES.ini*
+
+*$AOI* The name of the executing *AOI*
+
+*$PROCESSOR* The name of the executing *Processor*
+
+*$CWD* The current working directory, that expands to *$BASEPATH/$AOI/$PROCESSOR*
+
+*$STAMPS_PATH* The path for Stamp files configured in *DES.ini*
+
+*$FILE* Iff *<FileType>* is configured, references the current File being processed (*<ProductType>* is deprecated but still valid for backward compatibility)
+
+*$YEAR* The current year
+
+*$MONTH* The current month
+
+*$DAY* The current day