diff --git a/src/net/sourceforge/plantuml/plasma/PEntry.java b/src/net/sourceforge/plantuml/plasma/PEntry.java
index 8c84e31ee..1b0e667aa 100644
--- a/src/net/sourceforge/plantuml/plasma/PEntry.java
+++ b/src/net/sourceforge/plantuml/plasma/PEntry.java
@@ -35,6 +35,16 @@
  */
 package net.sourceforge.plantuml.plasma;
 
+/**
+ * Keeps track of the {@link Quark} objects that have a given name. Short for
+ * {@link Plasma} entry.
+ * 
+ * <p>
+ * Tracks the first instace created with that name, as well as the number of
+ * quarks with that name.
+ *
+ * @see Plasma#stats
+ */
 class PEntry<DATA> {
     // ::remove folder when __HAXE__
 
diff --git a/src/net/sourceforge/plantuml/plasma/Plasma.java b/src/net/sourceforge/plantuml/plasma/Plasma.java
index b592d6221..b5a01931c 100644
--- a/src/net/sourceforge/plantuml/plasma/Plasma.java
+++ b/src/net/sourceforge/plantuml/plasma/Plasma.java
@@ -42,6 +42,11 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+/**
+ * A namespace for {@link Quark} objects.
+ *
+ * @see net.sourceforge.plantuml.plasma
+ */
 public class Plasma<DATA> {
 
 	private String separator = "\u0000";
diff --git a/src/net/sourceforge/plantuml/plasma/Quark.java b/src/net/sourceforge/plantuml/plasma/Quark.java
index 9c0b26fc1..b20106ef5 100644
--- a/src/net/sourceforge/plantuml/plasma/Quark.java
+++ b/src/net/sourceforge/plantuml/plasma/Quark.java
@@ -40,6 +40,11 @@ import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+/**
+ * A named node in the entity graph.
+ *
+ * @see net.sourceforge.plantuml.plasma
+ */
 public class Quark<DATA> {
 
 	private final Plasma<DATA> plasma;
diff --git a/src/net/sourceforge/plantuml/plasma/package-info.java b/src/net/sourceforge/plantuml/plasma/package-info.java
new file mode 100644
index 000000000..a89d3f032
--- /dev/null
+++ b/src/net/sourceforge/plantuml/plasma/package-info.java
@@ -0,0 +1,47 @@
+/* ========================================================================
+ * PlantUML : a free UML diagram generator
+ * ========================================================================
+ *
+ * (C) Copyright 2009-2024, Arnaud Roques
+ *
+ * Project Info:  https://plantuml.com
+ * 
+ * If you like this project or if you find it useful, you can support us at:
+ * 
+ * https://plantuml.com/patreon (only 1$ per month!)
+ * https://plantuml.com/paypal
+ * 
+ * This file is part of PlantUML.
+ *
+ * PlantUML is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * PlantUML distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+ * USA.
+ *
+ *
+ * Original Author:  Benjamin Davies
+ * 
+ *
+ */
+
+/**
+ * Provides {@link Plasma} and {@link Quark} classes.
+ * 
+ * <p>
+ * Class diagrams (and other free-form graphs) are represented as a tree of
+ * enities. The tree structure is represented using {@link Quark} objects, each
+ * of which corresponds to an {@link net.sourceforge.plantuml.abel.Entity}. The
+ * quark for an entity can be retrieved using a method on the entity, and
+ * vice-versa.
+ */
+package net.sourceforge.plantuml.plasma;