Document "PSystem" implied original meaning

src/net/sourceforge/plantuml/AbstractPSystem.java

@@ -67,6 +67,15 @@ import net.sourceforge.plantuml.utils.BlocLines;
 import net.sourceforge.plantuml.version.License;
 import net.sourceforge.plantuml.version.Version;
 
+/**
+ * An abstract class for all diagram classes.
+ * 
+ * <p>
+ * Short for "{@link net.sourceforge.plantuml.plasma plasma} system", although
+ * most newer diagram types do not use entities stored in a plasma.
+ *
+ * @see PSystemBuilder
+ */
 public abstract class AbstractPSystem implements Diagram {
 	// ::remove file when __HAXE__
 

src/net/sourceforge/plantuml/PSystemBuilder.java

@@ -114,6 +114,8 @@ import net.sourceforge.plantuml.yaml.YamlDiagramFactory;
  * <p>
  * Tries each of the factories (enumerated in the static block below) until one
  * succeeds.
+ *
+ * @see AbstractPSystem
  */
 public class PSystemBuilder {
 	// ::remove file when __HAXE__

src/net/sourceforge/plantuml/plasma/PEntry.java

@@ -37,7 +37,7 @@ package net.sourceforge.plantuml.plasma;
 
 /**
  * Keeps track of the {@link Quark} objects that have a given name. Short for
- * {@link Plasma} entry.
+ * "{@link Plasma} entry".
  * 
  * <p>
  * Tracks the first instace created with that name, as well as the number of