7. For your amusement…

This simple XSLT stylesheet:

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="3.0">
 
<xsl:template match="/">
  <doc>Hello, world.</doc>
</xsl:template>
 
</xsl:stylesheet>

compiles to this SEF file:

{"N":"package","when":"2021-10-21T10:08:22.824+01:00",
"expiry":"2021-11-15","id":"0","version":"30","packageVersion":"1",
"saxonProduct":"SAXON-EE","saxonVersion":"10.6",
"buildDateTime":"2021-10-21T10:08:22.825+01:00",
"target":"JS","targetVersion":"2","relocatable":"true",
"implicit":"true","C":[{"N":"co","id":"0","binds":"","C":[{"N":"mode",
"onNo":"TC","flags":"dW","patternSlots":"0","C":[{"N":"templateRule",
"prec":"0","prio":"-0.5","seq":"0","rank":"0","minImp":"0",
"slots":"0","matches":"ND","flags":"s","line":"5","module":"out.xsl",
"C":[{"N":"p.nodeTest","role":"match","test":"ND"},{"N":"elem",
"role":"action","defaultElementNS":"http:\/\/www.w3.org\/1999\/xhtml",
"ns":"xsl=~ xml=~","line":"6","name":"doc","nsuri":"",
"C":[{"N":"valueOf","flags":"l","C":[{"N":"str",
"val":"Hello, world."}]}]}]}]}]},{"N":"overridden"},{"N":"output",
"C":[{"N":"property",
"name":"Q{http:\/\/saxon.sf.net\/}stylesheet-version","value":"30"}]},
{"N":"decimalFormat"}],"Σ":"cd7c765a"}

Which you are not expected to be able to read. Pretty printing doesn’t help much.

{
  "N": "package",
  "when": "2021-10-21T10:08:22.824+01:00",
  "expiry": "2021-11-15",
  "id": "0",
  "version": "30",
  "packageVersion": "1",
  "saxonProduct": "SAXON-EE",
  "saxonVersion": "10.6",
  "buildDateTime": "2021-10-21T10:08:22.825+01:00",
  "target": "JS",
  "targetVersion": "2",
  "relocatable": "true",
  "implicit": "true",
  "C": [
    {
      "N": "co",
      "id": "0",
      "binds": "",
      "C": [
        {
          "N": "mode",
          "onNo": "TC",
          "flags": "dW",
          "patternSlots": "0",
          "C": [
            {
              "N": "templateRule",
              "prec": "0",
              "prio": "-0.5",
              "seq": "0",
              "rank": "0",
              "minImp": "0",
              "slots": "0",
              "matches": "ND",
              "flags": "s",
              "line": "5",
              "module": "out.xsl",
              "C": [
                {
                  "N": "p.nodeTest",
                  "role": "match",
                  "test": "ND"
                },
                {
                  "N": "elem",
                  "role": "action",
                  "defaultElementNS": "http://www.w3.org/1999/xhtml",
                  "ns": "xsl=~ xml=~",
                  "line": "6",
                  "name": "doc",
                  "nsuri": "",
                  "C": [
                    {
                      "N": "valueOf",
                      "flags": "l",
                      "C": [
                        {
                          "N": "str",
                          "val": "Hello, world."
                        }
                      ]
                    }
                  ]
                }
              ]
            }
          ]
        }
      ]
    },
    {
      "N": "overridden"
    },
    {
      "N": "output",
      "C": [
        {
          "N": "property",
          "name": "Q{http://saxon.sf.net/}stylesheet-version",
          "value": "30"
        }
      ]
    },
    {
      "N": "decimalFormat"
    }
  ],
  "Σ": "cd7c765a"
}

You should never have to read an SEF file. If only we were so lucky!