 such as a place to insert characters or one endpoint of a range of characters to delete. Indices have the syntax</p>
  
    <p>base modifier modifier modifier ...</p>
  
    <p>Where base gives a starting point and the modifiers adjust the index from the starting point (e.g. move forward or backward one character). Every index must contain a base, but the modifiers are optional.</p>
  
    <p>The base for an index must have one of the following forms:</p>
  
    <dl>
      <dt>(line . char)</dt>
    
     