txlyre
/
avram


			
				
					
						
						
							12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667
							<html lang="en">
<head>
<title>File Format - avram - a virtual machine code interpreter</title>
<meta http-equiv="Content-Type" content="text/html">
<meta name="description" content="avram - a virtual machine code interpreter">
<meta name="generator" content="makeinfo 4.13">
<link title="Top" rel="start" href="index.html#Top">
<link rel="up" href="Virtual-Machine-Specification.html#Virtual-Machine-Specification" title="Virtual Machine Specification">
<link rel="prev" href="Concrete-Syntax.html#Concrete-Syntax" title="Concrete Syntax">
<link rel="next" href="Representation-of-Numeric-and-Textual-Data.html#Representation-of-Numeric-and-Textual-Data" title="Representation of Numeric and Textual Data">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
<meta http-equiv="Content-Style-Type" content="text/css">
<style type="text/css"><!--
  pre.display { font-family:inherit }
  pre.format  { font-family:inherit }
  pre.smalldisplay { font-family:inherit; font-size:smaller }
  pre.smallformat  { font-family:inherit; font-size:smaller }
  pre.smallexample { font-size:smaller }
  pre.smalllisp    { font-size:smaller }
  span.sc    { font-variant:small-caps }
  span.roman { font-family:serif; font-weight:normal; } 
  span.sansserif { font-family:sans-serif; font-weight:normal; } 
--></style>
</head>
<body>
<div class="node">
<a name="File-Format"></a>
<p>
Next:&nbsp;<a rel="next" accesskey="n" href="Representation-of-Numeric-and-Textual-Data.html#Representation-of-Numeric-and-Textual-Data">Representation of Numeric and Textual Data</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="Concrete-Syntax.html#Concrete-Syntax">Concrete Syntax</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="Virtual-Machine-Specification.html#Virtual-Machine-Specification">Virtual Machine Specification</a>
<hr>
</div>

<h3 class="section">2.3 File Format</h3>

<p><a name="index-file-format-154"></a>A virtual code file consists of an optional text preamble, followed by
the concrete representation for a tree. The latter uses the
syntax described in the previous section. The purpose of this section is
to specify the remaining details of the file format.

   <p>The format for virtual code files may also be used for other purposes
by virtual code applications, as it is automatically detected and parsed
by <code>avram</code> when used in an input file, and can be automatically
written to output files at the discretion of the application.

   <p>Other than virtual code files, input files not conforming to this format
are not an error as far as <code>avram</code> is concerned, because they are
<a name="index-text-files-155"></a>assumed to be text files. Applications can detect in virtual code
the assumption that is made and report an error if appropriate.

   <p>Although the data file format includes no checksums or other explicit
<a name="index-checksums-156"></a>methods of error detection, the concrete syntax itself provides a
good measure of protection against undetected errors. The probability is
vanishingly small that a random alteration to any valid encoding leaves
it intact, because every bit in the sequence either mandates or
prohibits the occurrence of two more bits somewhere after it. Errors in
different parts of the file would have to be consistent with one another
to go unnoticed.

<ul class="menu">
<li><a accesskey="1" href="Preamble-Section.html#Preamble-Section">Preamble Section</a>
<li><a accesskey="2" href="Data-Section.html#Data-Section">Data Section</a>
</ul>

   </body></html>