Added head and tail functions. They work with portals: {./Example.md

***portalname head 2}

Backend/Portals.py

@@ -11,7 +11,9 @@ from Preview import ReadTextFile
 PortalFileTypes = {"markdown", "text"}
 
 MarkerPattern = re.compile(
-    r"\{(?:(?P<CrossPath>[^\s{}']+)\s+)?\*\*\*(?P<CrossName>[^\s*{}]+)\}"
+    r"\{(?:(?P<CrossPath>[^\s{}']+)\s+)?\*\*\*(?P<CrossName>[^\s*{}]+)"
+    r"(?:\s+(?P<CrossPipe>head|tail)\s+(?P<CrossPipeCount>\d+))?\}"
+    r"|\{(?P<PipePath>[^\s{}']+)\s+(?P<PipeMode>head|tail)\s+(?P<PipeCount>\d+)\}"
     r"|\{(?P<LinePath>[^\s{}']+)\s+'(?P<LineNumber>\d+)'\}"
     r"|\{\*\*(?P<LineName>[^\s*{}]+)\}"
     r"|\{\*(?P<BlockName>[^\s*{}]+)\}"
@@ -188,6 +190,30 @@ def _ResolveCrossFileReference(
     return _FindLocalDefinitions(Content).get(Name)
 
 
+def _ApplyPipe(Text: str, Mode: str, Count: int) -> str:
+    Lines = Text.splitlines()
+    Selected = Lines[:Count] if Mode == "head" else Lines[-Count:] if Count > 0 else []
+    return "\n".join(Selected)
+
+
+def _ResolveWholeFilePipe(
+    RootName: str,
+    RefererDirectory: str,
+    PathText: str,
+    Mode: str,
+    Count: int,
+    Username: str,
+    UserGroups: list[str],
+) -> str | None:
+    TargetRelativePath = _NormalizeRelativePath(RefererDirectory, PathText)
+    Content = _ReadAccessiblePortalSource(RootName, TargetRelativePath, Username, UserGroups)
+
+    if Content is None:
+        return None
+
+    return _ApplyPipe(_ResolveLocalPortals(Content), Mode, Count)
+
+
 def _ResolveLineNumberReference(
     RootName: str,
     RefererDirectory: str,
@@ -233,6 +259,20 @@ def ResolvePortals(
                 Username,
                 UserGroups,
             )
+            if Replacement is not None and Match.group("CrossPipe"):
+                Replacement = _ApplyPipe(
+                    Replacement, Match.group("CrossPipe"), int(Match.group("CrossPipeCount"))
+                )
+        elif Match.group("PipeMode"):
+            Replacement = _ResolveWholeFilePipe(
+                RootName,
+                RefererDirectory,
+                Match.group("PipePath"),
+                Match.group("PipeMode"),
+                int(Match.group("PipeCount")),
+                Username,
+                UserGroups,
+            )
         elif Match.group("LineNumber"):
             Replacement = _ResolveLineNumberReference(
                 RootName,