Getting Started with Java - Beginning Java 7 - page 19

Figure 1-4. The entry-point page into HelloWorld 's javadoc provides easy access to the docu-
mentation.
Note JDK7'sexternaldocumentationhasasimilarappearanceandorganizationto
Figure 1-4 because this documentation was also generated by javadoc .
Identifiers
Sourcecodeentitiessuchasclassesandmethodsneedtobenamedsothattheycanbe
referencedfromelsewhereinthecode.Javaprovidestheidentifiersfeatureforthispur-
pose.
An identifier consists of letters (A-Z, a-z, or equivalent uppercase/lowercase letters
in other human alphabets), digits (0-9 or equivalent digits in other human alphabets),
connectingpunctuationcharacters(e.g.,theunderscore),andcurrencysymbols(e.g.,the
dollar sign $). This name must begin with a letter, a currency symbol, or a connecting
punctuation character; and its length cannot exceed the line in which it appears.