private boolean isIdChar(int ch){
  return isAlpha(ch) || isDigit(ch) || ch == '.' || ch == '-' || ch == '_' || ch == ':' || Character.isLetter(ch);
}

private boolean isIdChar ( int ch ) { return isAlpha ( ch ) || isDigit ( ch ) || ch == '.' || ch == '-' || ch == '_' || ch == ':' || Character . isLetter ( ch ) ; }
from html 4 . 0 [ 4 ] namechar : : = letter | digit | ' . ' | ' - ' | ' _ ' | ' : ' | combiningchar | extender [ 5 ] name : : = ( letter | ' _ ' | ' : ' ) ( namechar ) [ 6 ] names : : = name ( # x20 name ) [ 7 ] nmtoken : : = ( namechar ) + [ 8 ] nmtokens : : = nmtoken ( # x20 nmtoken )
