diff --git a/Help/markdown/Table_of_Special_Functions.md b/Help/markdown/Table_of_Special_Functions.md
index 3dd15f7..bac5c35 100644
--- a/Help/markdown/Table_of_Special_Functions.md
+++ b/Help/markdown/Table_of_Special_Functions.md
@@ -16,6 +16,12 @@ The return types include:  **STR** (string), **INT** (integer), and **BOOL** (B
 | [**findana**](findana.md) | **BOOL(1,0)** | See if named project is already resident in memory. **(New in 1.6)** |
 | [**hitconf(hits_num, total_num, fudge_num)**](hitconf.md) | **INT (0 to 100)** | Calculate the keyword density. Fudge factor is typically 3 to 20. |
 | [**interactive()**](interactive.md) | **BOOL(1,0)** | True if analyzer is being run in an interactive environment, e.g., inside VisualText. |
+| [**isarray(value)**](isarray.md) | **BOOL(1,0)** | True if the value is an array (more than one element). **(New in 4.2.34)** |
+| [**iscon(value)**](iscon.md) | **BOOL(1,0)** | True if the value is a knowledge base concept. **(New in 4.2.34)** |
+| [**isfloat(value)**](isfloat.md) | **BOOL(1,0)** | True if the value is a floating-point number. **(New in 4.2.34)** |
+| [**isnum(value)**](isnum.md) | **BOOL(1,0)** | True if the value is an integer. An unset variable reads as 0, so it is one. **(New in 4.2.34)** |
+| [**ispn(value)**](ispn.md) | **BOOL(1,0)** | True if the value is a parse tree node. **(New in 4.2.34)** |
+| [**isstr(value)**](isstr.md) | **BOOL(1,0)** | True if the value is a string, including "" and digit strings. **(New in 4.2.34)** |
 | [**mkdir(dir_str)**](mkdir.md) | **BOOL(1,0)** | Create a directory. Operating system-dependent. |
 | [**permuten(tot_num)**](permuten.md) | **INT ARR** | Permute integers 0 to (tot_num - 1) such that array element k will never be equal to k. |
 | [**succeed()**](succeed.md) | **NONE** | In CHECK Region and CODE Region, succeed without executing further code. See fail(). |
diff --git a/Help/markdown/index.md b/Help/markdown/index.md
index a7387f5..e1dc0be 100644
--- a/Help/markdown/index.md
+++ b/Help/markdown/index.md
@@ -446,6 +446,12 @@ to a topic.
         - [findana](findana.md)
         - [hitconf](hitconf.md)
         - [interactive](interactive.md)
+        - [isarray](isarray.md)
+        - [iscon](iscon.md)
+        - [isfloat](isfloat.md)
+        - [isnum](isnum.md)
+        - [ispn](ispn.md)
+        - [isstr](isstr.md)
         - [mkdir](mkdir.md)
         - [permuten](permuten.md)
         - [sortconsbyattr](sortconsbyattr.md)
diff --git a/Help/markdown/isarray.md b/Help/markdown/isarray.md
new file mode 100644
index 0000000..8300654
--- /dev/null
+++ b/Help/markdown/isarray.md
@@ -0,0 +1,47 @@
+[← Help Contents](index.md) | [📘 NLP++ Textbook](NLP++_Textbook.md)
+
+# isarray
+
+## Purpose
+
+Test whether a value is an array: a value with more than one element.
+
+## Syntax
+
+```
+returnedBool = isarray(value)
+```
+
+```
+returnedBool - type: bool
+
+value - any value: a string, number, concept, parse tree node or array
+```
+
+## Returns
+
+1 if the value is an array: a value with more than one element; otherwise 0.
+
+## Remarks
+
+NLP++ is loosely typed, and a function given the wrong kind of value often fails without saying so. **isarray** and the other type tests let code check first. They accept any value and never print a warning, even for an empty one. Pass exactly one argument.
+
+**NEW 4.2.34**
+
+## Example
+
+```
+@CODE
+
+L("a")[0] = "x";
+L("a")[1] = "y";
+"output.txt" << isarray(L("a")) << "\n";   # 1
+
+@@CODE
+```
+
+## See Also
+
+[iscon](iscon.md), [isstr](isstr.md), [isnum](isnum.md), [isfloat](isfloat.md), [ispn](ispn.md), [pnvartype](pnvartype.md)
+
+[Special Functions](Table_of_Special_Functions.md)
diff --git a/Help/markdown/iscon.md b/Help/markdown/iscon.md
new file mode 100644
index 0000000..3444860
--- /dev/null
+++ b/Help/markdown/iscon.md
@@ -0,0 +1,47 @@
+[← Help Contents](index.md) | [📘 NLP++ Textbook](NLP++_Textbook.md)
+
+# iscon
+
+## Purpose
+
+Test whether a value is a knowledge base concept.
+
+## Syntax
+
+```
+returnedBool = iscon(value)
+```
+
+```
+returnedBool - type: bool
+
+value - any value: a string, number, concept, parse tree node or array
+```
+
+## Returns
+
+1 if the value is a knowledge base concept; otherwise 0.
+
+## Remarks
+
+NLP++ is loosely typed, and a function given the wrong kind of value often fails without saying so. **iscon** and the other type tests let code check first. They accept any value and never print a warning, even for an empty one. Pass exactly one argument.
+
+**NEW 4.2.34**
+
+## Example
+
+```
+@CODE
+
+L("c") = findconcept(findroot(), "colors");
+if (!iscon(L("c")))
+    L("c") = makeconcept(findroot(), "colors");
+
+@@CODE
+```
+
+## See Also
+
+[isstr](isstr.md), [isnum](isnum.md), [isfloat](isfloat.md), [ispn](ispn.md), [isarray](isarray.md), [pnvartype](pnvartype.md)
+
+[Special Functions](Table_of_Special_Functions.md)
diff --git a/Help/markdown/isfloat.md b/Help/markdown/isfloat.md
new file mode 100644
index 0000000..8a02502
--- /dev/null
+++ b/Help/markdown/isfloat.md
@@ -0,0 +1,46 @@
+[← Help Contents](index.md) | [📘 NLP++ Textbook](NLP++_Textbook.md)
+
+# isfloat
+
+## Purpose
+
+Test whether a value is a floating-point number.
+
+## Syntax
+
+```
+returnedBool = isfloat(value)
+```
+
+```
+returnedBool - type: bool
+
+value - any value: a string, number, concept, parse tree node or array
+```
+
+## Returns
+
+1 if the value is a floating-point number; otherwise 0.
+
+## Remarks
+
+NLP++ is loosely typed, and a function given the wrong kind of value often fails without saying so. **isfloat** and the other type tests let code check first. They accept any value and never print a warning, even for an empty one. Pass exactly one argument.
+
+**NEW 4.2.34**
+
+## Example
+
+```
+@CODE
+
+L("x") = 4.5;
+"output.txt" << isfloat(L("x")) << "\n";   # 1
+
+@@CODE
+```
+
+## See Also
+
+[iscon](iscon.md), [isstr](isstr.md), [isnum](isnum.md), [ispn](ispn.md), [isarray](isarray.md), [pnvartype](pnvartype.md)
+
+[Special Functions](Table_of_Special_Functions.md)
diff --git a/Help/markdown/isnum.md b/Help/markdown/isnum.md
new file mode 100644
index 0000000..7f5b141
--- /dev/null
+++ b/Help/markdown/isnum.md
@@ -0,0 +1,46 @@
+[← Help Contents](index.md) | [📘 NLP++ Textbook](NLP++_Textbook.md)
+
+# isnum
+
+## Purpose
+
+Test whether a value is an integer.
+
+## Syntax
+
+```
+returnedBool = isnum(value)
+```
+
+```
+returnedBool - type: bool
+
+value - any value: a string, number, concept, parse tree node or array
+```
+
+## Returns
+
+1 if the value is an integer; otherwise 0.
+
+## Remarks
+
+NLP++ is loosely typed, and a function given the wrong kind of value often fails without saying so. **isnum** and the other type tests let code check first. They accept any value and never print a warning, even for an empty one. Pass exactly one argument. A variable that was never set reads as 0 in NLP++, so it counts as an integer.
+
+**NEW 4.2.34**
+
+## Example
+
+```
+@CODE
+
+if (isnum(N("count", 1)) && N("count", 1) > 2)
+    "output.txt" << "frequent\n";
+
+@@CODE
+```
+
+## See Also
+
+[iscon](iscon.md), [isstr](isstr.md), [isfloat](isfloat.md), [ispn](ispn.md), [isarray](isarray.md), [pnvartype](pnvartype.md)
+
+[Special Functions](Table_of_Special_Functions.md)
diff --git a/Help/markdown/ispn.md b/Help/markdown/ispn.md
new file mode 100644
index 0000000..4aeb8ba
--- /dev/null
+++ b/Help/markdown/ispn.md
@@ -0,0 +1,47 @@
+[← Help Contents](index.md) | [📘 NLP++ Textbook](NLP++_Textbook.md)
+
+# ispn
+
+## Purpose
+
+Test whether a value is a parse tree node.
+
+## Syntax
+
+```
+returnedBool = ispn(value)
+```
+
+```
+returnedBool - type: bool
+
+value - any value: a string, number, concept, parse tree node or array
+```
+
+## Returns
+
+1 if the value is a parse tree node; otherwise 0.
+
+## Remarks
+
+NLP++ is loosely typed, and a function given the wrong kind of value often fails without saying so. **ispn** and the other type tests let code check first. They accept any value and never print a warning, even for an empty one. Pass exactly one argument.
+
+**NEW 4.2.34**
+
+## Example
+
+```
+@CODE
+
+L("n") = N("head", 1);
+if (ispn(L("n")))
+    "output.txt" << pnname(L("n")) << "\n";
+
+@@CODE
+```
+
+## See Also
+
+[iscon](iscon.md), [isstr](isstr.md), [isnum](isnum.md), [isfloat](isfloat.md), [isarray](isarray.md), [pnvartype](pnvartype.md)
+
+[Special Functions](Table_of_Special_Functions.md)
diff --git a/Help/markdown/isstr.md b/Help/markdown/isstr.md
new file mode 100644
index 0000000..77027fa
--- /dev/null
+++ b/Help/markdown/isstr.md
@@ -0,0 +1,46 @@
+[← Help Contents](index.md) | [📘 NLP++ Textbook](NLP++_Textbook.md)
+
+# isstr
+
+## Purpose
+
+Test whether a value is a string.
+
+## Syntax
+
+```
+returnedBool = isstr(value)
+```
+
+```
+returnedBool - type: bool
+
+value - any value: a string, number, concept, parse tree node or array
+```
+
+## Returns
+
+1 if the value is a string; otherwise 0.
+
+## Remarks
+
+NLP++ is loosely typed, and a function given the wrong kind of value often fails without saying so. **isstr** and the other type tests let code check first. They accept any value and never print a warning, even for an empty one. Pass exactly one argument. A string of digits such as "42" is a string, and so is the empty string "".
+
+**NEW 4.2.34**
+
+## Example
+
+```
+@CODE
+
+if (isstr(N("lemma", 1)))
+    "lemmas.txt" << N("lemma", 1) << "\n";
+
+@@CODE
+```
+
+## See Also
+
+[iscon](iscon.md), [isnum](isnum.md), [isfloat](isfloat.md), [ispn](ispn.md), [isarray](isarray.md), [pnvartype](pnvartype.md)
+
+[Special Functions](Table_of_Special_Functions.md)