Bug 56965 Classpath variable name has to be a valid Java identifier
I20040330 window>preferences>java>classpath variables>new type '444' an error is displayed in the dialog : Invalid name: ''444' is not a valid Java identifier.'. I don't see any reason why the name of the variable has to be a valid Java identifier.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/VariableCreationDialog.java
protected void configureShell(Shell newShell) {
		super.configureShell(newShell);
		WorkbenchHelp.setHelp(newShell, IJavaHelpContextIds.VARIABLE_CREATION_DIALOG);
	}
	
	public CPVariableElement getClasspathElement() {
		return new CPVariableElement(fNameField.getText(), new Path(fPathField.getText()), false);
	}
	/*
	 * @see Dialog#createDialogArea(org.eclipse.swt.widgets.Composite)
	 */	
	protected Control createDialogArea(Composite parent) {
		Composite composite= (Composite)super.createDialogArea(parent);
		
		PixelConverter converter= new PixelConverter(parent);
		
		Composite inner= new Composite(composite, SWT.NONE);
		
		GridLayout layout= new GridLayout();
		layout.marginWidth= 0;
		layout.numColumns= 3;
		inner.setLayout(layout);
		
		int fieldWidthHint= converter.convertWidthInCharsToPixels(50);
		
		fNameField.doFillIntoGrid(inner, 2);
		LayoutUtil.setWidthHint(fNameField.getTextControl(null), fieldWidthHint);
		LayoutUtil.setHorizontalGrabbing(fNameField.getTextControl(null));
		
		DialogField.createEmptySpace(inner, 1);