diff --git a/Ghidra/Features/Base/src/main/java/ghidra/program/flatapi/FlatProgramAPI.java b/Ghidra/Features/Base/src/main/java/ghidra/program/flatapi/FlatProgramAPI.java
index 33933b397e..b5d5f5cc96 100644
--- a/Ghidra/Features/Base/src/main/java/ghidra/program/flatapi/FlatProgramAPI.java
+++ b/Ghidra/Features/Base/src/main/java/ghidra/program/flatapi/FlatProgramAPI.java
@@ -246,7 +246,7 @@ public class FlatProgramAPI {
 	/**
 	 * Clears the code units (instructions or data) in the specified range.
 	 * @param start the start address
-	 * @param end   the end address
+	 * @param end   the end address (INCLUSIVE)
 	 * @throws CancelledException if cancelled
 	 */
 	public final void clearListing(Address start, Address end) throws CancelledException {
@@ -1506,7 +1506,7 @@ public class FlatProgramAPI {
 	/**
 	 * Returns the non-function namespace with the given name contained inside the
 	 * specified parent namespace.
-	 * Pass <code>null</code> for namespace to indicate the global namespace.
+	 * Pass <code>null</code> for parent to indicate the global namespace.
 	 * @param parent the parent namespace, or null for global namespace
 	 * @param namespaceName the requested namespace's name
 	 * @return the namespace with the given name or null if not found
@@ -1514,6 +1514,66 @@ public class FlatProgramAPI {
 	public final Namespace getNamespace(Namespace parent, String namespaceName) {
 		return currentProgram.getSymbolTable().getNamespace(namespaceName, parent);
 	}
+	
+/**
+	 * Creates a new {@link Namespace} with the given name contained inside the
+	 * specified parent namespace.
+	 * Pass <code>null</code> for parent to indicate the global namespace.
+	 * If a {@link Namespace} or {@link GhidraClass} with the given name already exists, the
+	 * existing one will be returned.
+	 * @param parent the parent namespace, or null for global namespace
+	 * @param namespaceName the requested namespace's name
+	 * @return the namespace with the given name
+	 * @throws DuplicateNameException if a {@link Library} symbol exists with the given name
+	 * @throws InvalidInputException if the name is invalid
+	 * @throws IllegalArgumentException if parent Namespace does not correspond to
+	 * <code>currerntProgram</code>
+	 */
+	public final Namespace createNamespace(Namespace parent, String namespaceName)
+			throws DuplicateNameException, InvalidInputException {
+		SymbolTable symbolTable = currentProgram.getSymbolTable();
+		Namespace ns = symbolTable.getNamespace(namespaceName, parent);
+		if (ns != null) {
+			SymbolType type = ns.getSymbol().getSymbolType();
+			if (type == SymbolType.NAMESPACE || type == SymbolType.CLASS) {
+				return ns;
+			}
+		}
+		return symbolTable.createNameSpace(parent, namespaceName, SourceType.USER_DEFINED);
+	}
+	
+	/**
+	 * Creates a new {@link GhidraClass} with the given name contained inside the
+	 * specified parent namespace.
+	 * Pass <code>null</code> for parent to indicate the global namespace.
+	 * If a GhidraClass with the given name already exists, the existing one will be returned.
+	 * @param parent the parent namespace, or null for global namespace
+	 * @param className the requested classes name
+	 * @return the GhidraClass with the given name
+	 * @throws InvalidInputException if the name is invalid
+	 * @throws DuplicateNameException thrown if a {@link Library} or {@link Namespace}
+	 * symbol already exists with the given name.
+	 * Use {@link SymbolTable#convertNamespaceToClass(Namespace)} for converting an
+	 * existing Namespace to a GhidraClass.
+	 * @throws IllegalArgumentException if the given parent namespace is not from
+	 * the {@link #currentProgram}.
+	 * @throws ConcurrentModificationException if the given parent has been deleted
+	 * @throws IllegalArgumentException if parent Namespace does not correspond to
+	 * <code>currerntProgram</code>
+	 * @see SymbolTable#convertNamespaceToClass(Namespace)
+	 */
+	public final GhidraClass createClass(Namespace parent, String className)
+			throws DuplicateNameException, InvalidInputException {
+		SymbolTable symbolTable = currentProgram.getSymbolTable();
+		Namespace ns = symbolTable.getNamespace(className, parent);
+		if (ns != null) {
+			SymbolType type = ns.getSymbol().getSymbolType();
+			if (type == SymbolType.CLASS) {
+				return (GhidraClass) ns;
+			}
+		}
+		return symbolTable.createClass(parent, className, SourceType.USER_DEFINED);
+	}
 
 	/**
 	 * Creates a fragment in the root folder of the default program tree.
diff --git a/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/symbol/SymbolManager.java b/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/symbol/SymbolManager.java
index 8657972ff9..ee31fac974 100644
--- a/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/symbol/SymbolManager.java
+++ b/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/symbol/SymbolManager.java
@@ -2579,6 +2579,11 @@ public class SymbolManager implements SymbolTable, ManagerDB {
 
 			checkValidNamespaceArgument(namespace);
 
+			if (namespace.isGlobal() || namespace.isLibrary()) {
+				throw new IllegalArgumentException(
+					"May not convert namespace to class: " + namespace.getName(true));
+			}
+
 			Symbol namespaceSymbol = namespace.getSymbol();
 			String name = namespaceSymbol.getName();
 			SourceType originalSource = namespaceSymbol.getSource();
@@ -2729,7 +2734,7 @@ public class SymbolManager implements SymbolTable, ManagerDB {
 	 * it will be returned.
 	 * @param addr the address for the new symbol (memory or external)
 	 * @param name the name of the new symbol
-	 * @param namespace the namespace for the new symbol
+	 * @param namespace the namespace for the new symbol (null may be specified for global namespace)
 	 * @param source the SourceType of the new symbol
 	 * @param stringData special use depending on the symbol type and whether or not it is external
 	 * @return the new symbol
@@ -2789,7 +2794,7 @@ public class SymbolManager implements SymbolTable, ManagerDB {
 	 * 
 	 * @param addr the address for the new symbol
 	 * @param name the name of the new symbol
-	 * @param namespace the namespace for the new symbol
+	 * @param namespace the namespace for the new symbol (null may be specified for global namespace)
 	 * @param source the SourceType of the new symbol
 	 * @param stringData special use depending on the symbol type and whether or not it is external.
 	 * @return the new symbol
diff --git a/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/symbol/SymbolTable.java b/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/symbol/SymbolTable.java
index 43096be32b..3c97f23937 100644
--- a/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/symbol/SymbolTable.java
+++ b/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/symbol/SymbolTable.java
@@ -86,7 +86,8 @@ public interface SymbolTable {
 	 * @throws InvalidInputException thrown if names contains white space, is zero length, or is
 	 * null for non-default source.  Also thrown if invalid parentNamespace is specified.
 	 * @throws IllegalArgumentException if you try to set the source to DEFAULT for a symbol type
-	 * that doesn't allow it, or an improper addr is specified
+	 * that doesn't allow it, specify an improper addr, or specify a namespace which does not 
+	 * correspond to this symbol table's program.
 	 */
 	public Symbol createLabel(Address addr, String name, Namespace namespace, SourceType source)
 			throws InvalidInputException;
@@ -137,6 +138,8 @@ public interface SymbolTable {
 	 * @param namespace the namespace of the symbol to retrieve. May be null which indicates global
 	 * namespace.
 	 * @return the symbol which matches the specified criteria or null if not found
+	 * @throws IllegalArgumentException amespace which does not correspond to this 
+	 * symbol table's program.
 	 * @see #getGlobalSymbol(String, Address) for a convenience method if the namespace is the
 	 * global namespace.
 	 */
@@ -182,6 +185,8 @@ public interface SymbolTable {
 	 * @param name the name of the symbols to search for.
 	 * @param namespace the namespace to search.  If null, then the global namespace is assumed.
 	 * @return a list of all the label or function symbols with the given name in the given namespace.
+	 * @throws IllegalArgumentException amespace which does not correspond to this 
+	 * symbol table's program.
 	 */
 	public List<Symbol> getLabelOrFunctionSymbols(String name, Namespace namespace);
 
@@ -190,6 +195,8 @@ public interface SymbolTable {
 	 * @param name the name of the namespace symbol to retrieve.
 	 * @param namespace the namespace containing the symbol to retrieve.
 	 * @return a generic namespace symbol with the given name in the given namespace.
+	 * @throws IllegalArgumentException amespace which does not correspond to this 
+	 * symbol table's program.
 	 */
 	public Symbol getNamespaceSymbol(String name, Namespace namespace);
 
@@ -205,6 +212,8 @@ public interface SymbolTable {
 	 * @param name the name of the class.
 	 * @param namespace the namespace to search for the class.
 	 * @return the class symbol with the given name in the given namespace.
+	 * @throws IllegalArgumentException amespace which does not correspond to this 
+	 * symbol table's program.
 	 */
 	public Symbol getClassSymbol(String name, Namespace namespace);
 
@@ -213,6 +222,8 @@ public interface SymbolTable {
 	 * @param name the name of the parameter.
 	 * @param namespace the namespace (function) to search for the class.
 	 * @return the parameter symbol with the given name in the given namespace.
+	 * @throws IllegalArgumentException amespace which does not correspond to this 
+	 * symbol table's program.
 	 */
 	public Symbol getParameterSymbol(String name, Namespace namespace);
 
@@ -221,6 +232,8 @@ public interface SymbolTable {
 	 * @param name the name of the local variable.
 	 * @param namespace the namespace (function) to search for the class.
 	 * @return the local variable symbol with the given name in the given namespace.
+	 * @throws IllegalArgumentException amespace which does not correspond to this 
+	 * symbol table's program.
 	 */
 	public Symbol getLocalVariableSymbol(String name, Namespace namespace);
 
@@ -233,6 +246,8 @@ public interface SymbolTable {
 	 * @param name the name of the symbols to retrieve.
 	 * @param namespace the namespace to search for symbols.
 	 * @return all symbols which satisfy specified criteria
+	 * @throws IllegalArgumentException amespace which does not correspond to this 
+	 * symbol table's program.
 	 */
 	public List<Symbol> getSymbols(String name, Namespace namespace);
 
@@ -252,6 +267,8 @@ public interface SymbolTable {
 	 * @param name the name of the namespace to be retrieved.
 	 * @param namespace the parent namespace of the namespace to be retrieved.
 	 * @return the namespace with the given name in the given parent namespace.
+	 * @throws IllegalArgumentException amespace which does not correspond to this 
+	 * symbol table's program.
 	 */
 	public Namespace getNamespace(String name, Namespace namespace);
 
@@ -333,6 +350,8 @@ public interface SymbolTable {
 	 * 
 	 * @param namespace the namespace to search for symbols.
 	 * @return symbol iterator
+	 * @throws IllegalArgumentException amespace which does not correspond to this 
+	 * symbol table's program.
 	 */
 	public SymbolIterator getSymbols(Namespace namespace);
 
@@ -527,14 +546,15 @@ public interface SymbolTable {
 
 	/**
 	 * Create a class namespace in the given parent namespace.
-	 * @param parent parent namespace
+	 * @param parent parent namespace (may be null for global namespace)
 	 * @param name name of the namespace
 	 * @param source the source of this class namespace's symbol
 	 * @return new class namespace
 	 * @throws DuplicateNameException thrown if another non function or label symbol exists with
 	 * the given name
 	 * @throws InvalidInputException throw if the name has invalid characters or is null
-	 * @throws IllegalArgumentException if you try to set the source to 'Symbol.DEFAULT'.
+	 * @throws IllegalArgumentException if you try to set the source to 'Symbol.DEFAULT'
+	 * or specify a parent Namespace which does not correspond to this symbol table's program.
 	 */
 	public GhidraClass createClass(Namespace parent, String name, SourceType source)
 			throws DuplicateNameException, InvalidInputException;
@@ -565,14 +585,15 @@ public interface SymbolTable {
 
 	/**
 	 * Creates a new namespace.
-	 * @param parent the parent namespace for the new namespace
+	 * @param parent the parent namespace for the new namespace (may be null for global namespace)
 	 * @param name the name of the new namespace
 	 * @param source the source of this namespace's symbol
 	 * @return the new Namespace object.
 	 * @throws DuplicateNameException thrown if another non function or label symbol
 	 * exists with the given name
 	 * @throws InvalidInputException if the name is invalid.
-	 * @throws IllegalArgumentException if you try to set the source to 'Symbol.DEFAULT'.
+	 * @throws IllegalArgumentException if you try to set the source to 'Symbol.DEFAULT'
+	 * or specify a parent Namespace which does not correspond to this symbol table's program.
 	 */
 	public Namespace createNameSpace(Namespace parent, String name, SourceType source)
 			throws DuplicateNameException, InvalidInputException;
@@ -585,6 +606,8 @@ public interface SymbolTable {
 	 * @throws IllegalArgumentException if the given parent namespace is from a different program
 	 *         than that of this symbol table
 	 * @throws ConcurrentModificationException if the given parent namespace has been deleted
+	 * @throws IllegalArgumentException namespace does not correspond to this symbol table's program
+	 * or namespace not allowed (e.g., global or library namespace).
 	 */
 	public GhidraClass convertNamespaceToClass(Namespace namespace);