Check Functions
| IsAffirm | Checks if passed char is an affirmation char |
| IsAlpha | Checks if leftmost character in a string is an alphabetic character |
| IsBin | Check if the value is a Binary Number |
| IsDec | Check if the value is a Decimal Number |
| IsDigit | Checks if leftmost character is a digit character |
| IsDisk | Verify if a drive is ready |
| IsHexa | Check if the value is a Hexal Number |
| IsLeap | Tests if a specific year is a leap year |
| IsLeapYear | Checks if the given date is a leap year |
| IsLower | Checks if leftmost character is an lowercased letter |
| IsNegative | Checks if passed char is a negation char |
| IsOctal | Check if the value is a Octal Number |
| IsUpper | Checks if leftmost character is an uppercased letter. |
| HB_Is_CStructure | Checks if the value is a CStructure |
| HB_IsArray | Tests if the value returned by an expression is an array |
| HB_IsBlock | Tests if the value returned by an expression is a Code block |
| HB_IsByRef | Tests if a parameter is passed by reference |
| HB_IsChar | Tests if the value returned by an expression is char type |
| HB_IsDate | Tests if the value returned by an expression is a Date |
| HB_IsDateTime | Tests if the value returned by an expression is a DateTime value |
| HB_IsEvalItem | Undocumented |
| hb_IsFunction | Determine wheter exists (linkable) a function |
| HB_IsHash | Tests if the value returned by an expression is a Hash |
| HB_IsHashKey | Tests if the value returned by an expression is a Hash Key |
| HB_IsLogical | Tests if the value returned by an expression is a logical value |
| HB_IsMemo | Tests if the value returned by an expression is a Memo value |
| HB_IsNil | Tests if the value returned by an expression is NIL |
| HB_IsNull | Tests if the value returned by an expression is empty |
| HB_IsNumeric | Tests if the value returned by an expression is a numeric value |
| HB_IsObject | Tests if the value returned by an expression is an object |
| HB_IsPointer | Tests if the value returned by an expression is a pointer |
| hb_IsPrinter | ( Probably ) same as IsPrinter() |
| hb_IsRegex | Determine is this value a regular expression |
| hb_IsRegexString | Checks if a character string is a compiled regular expression |
| hb_IsService | Undocumented |
| HB_IsString | Checks if the value is a string |
| HB_IsSymbol | Checks if the value is a symbol |
| HB_IsTimeStamp | Checks if the value is a TimeStamp |
