Clarify empty multiline string behavior

Author: antonmedv

spec/v0.1.md

@@ -13,7 +13,6 @@ Objectives
 2. MAML should be easily readable by humans.
 3. MAML should be easily parsed by machines.
 
-
 Spec
 ----
 
@@ -72,7 +71,6 @@ Commas are optional. Trailing comma is allowed.
 [ "red", "yellow", "green", ]
 ```
 
-
 Objects
 -------
 
@@ -225,6 +223,25 @@ Multiline string may also be written in a single line.
 """A multiline string and with "quotas"."""
 ```
 
+The following example evaluates to the empty string `""`:
+
+```maml
+"""
+"""
+```
+
+If you want a string that contains exactly one newline character, insert one 
+additional blank line between the delimiters:
+
+```maml
+"""
+
+"""
+```
+
+The single-line multiline string cannot represent an empty string. To write an 
+empty string on one line, use a normal string `""`.
+
 All multiline strings must contain only valid UTF-8 characters.
 
 
@@ -292,7 +309,6 @@ Booleans are `true` and `false`. Always lowercase.
 [ true, false ]
 ```
 
-
 Null
 ----
 
@@ -303,7 +319,6 @@ valid and different from not having that key in the object. Always lowercase.
 null
 ```
 
-
 Filename Extension
 ------------------
 
@@ -323,7 +338,7 @@ ABNF Grammar
 A formal description of MAML's syntax in ABNF format
 ([RFC 5234](https://www.ietf.org/rfc/rfc5234.txt)).
 
-A visual representation of the MAML syntax is available in the 
+A visual representation of the MAML syntax is available in the
 [syntax diagram](/spec/v0.1/diagram.md).
 
 <<< @/spec/v0.1/maml.abnf