diff --git a/spec/formatting.md b/spec/formatting.md
index a4f34eea41..6479096ebe 100644
--- a/spec/formatting.md
+++ b/spec/formatting.md
@@ -40,7 +40,7 @@ These are divided into the following categories:
   ```
 
   ```
-  {Unknown {#placeholder#}}
+  {Unknown {#expression#}}
   ```
 
   ```
@@ -186,8 +186,8 @@ or contains some error which leads to further errors,
 an implementation which does not emit all of the errors
 should prioritise Syntax and Data Model errors over others.
 
-When an error occurs in the resolution of an Expression or Markup Option,
-the Expression or Markup in question is processed as if the option were not defined.
+When an error occurs in the resolution of an Expression,
+the Expression in question is processed as if the option were not defined.
 This may allow for the fallback handling described below to be avoided,
 though an error must still be emitted.
 
@@ -205,8 +205,8 @@ If a fallback string is not defined,
 the U+FFFD REPLACEMENT CHARACTER `�` character is used,
 resulting in the string `{�}`.
 
-When an error occurs in a Placeholder that is being formatted,
-the fallback string representation of the Placeholder
+When an error occurs in an Expression that is being formatted,
+the fallback string representation of the Expression
 always starts with U+007B LEFT CURLY BRACKET `{`
 and ends with U+007D RIGHT CURLY BRACKET `}`.
 Between the brackets, the following contents are used:
@@ -222,15 +222,15 @@ Between the brackets, the following contents are used:
 
   Example: `{$user}`
 
-- Expression with no Operand: U+003A COLON `:` followed by the Expression Name
+- Standalone expression with no Operand: U+003A COLON `:` followed by the Expression Name
 
   Example: `{:platform}`
 
-- Markup start: U+002B PLUS SIGN `+` followed by the MarkupStart Name
+- Opening expression with no Operand: U+002B PLUS SIGN `+` followed by the Expression Name
 
   Example: `{+tag}`
 
-- Markup end: U+002D HYPHEN-MINUS `-` followed by the MarkupEnd Name
+- Closing expression with no Operand: U+002D HYPHEN-MINUS `-` followed by the Expression Name
 
   Example: `{-tag}`
 
@@ -243,7 +243,7 @@ Option names and values are not included in the fallback string representations.
 When an error occurs in an Expression with a Variable Operand
 and the Variable refers to a local variable Declaration,
 the fallback string is formatted based on the Expression of the Declaration,
-rather than the Expression of the Placeholder.
+rather than the Expression in the Selector or Pattern.
 
 For example, attempting to format either of the following messages within a context that
 does not provide for the function `:func` to be successfully resolved:
diff --git a/spec/message.abnf b/spec/message.abnf
index 66512a3189..b869a761fe 100644
--- a/spec/message.abnf
+++ b/spec/message.abnf
@@ -1,21 +1,15 @@
 message = [s] *(declaration [s]) body [s]
 
-declaration = let s variable [s] "=" [s] "{" [s] expression [s] "}"
+declaration = let s variable [s] "=" [s] expression
 body = pattern
      / (selectors 1*([s] variant))
 
-pattern = "{" *(text / placeholder) "}"
-selectors = match 1*([s] selector)
-selector = "{" [s] expression [s] "}"
+pattern = "{" *(text / expression) "}"
+selectors = match 1*([s] expression)
 variant = when 1*(s key) [s] pattern
 key = nmtoken / literal / "*"
 
-placeholder = "{" [s] expression [s] "}"
-            / "{" [s] markup-start *(s option) [s] "}"
-            / "{" [s] markup-end [s] "}"
-
-expression = ((literal / variable) [s annotation])
-           / annotation
+expression = "{" [s] (((literal / variable) [s annotation]) / annotation) [s] "}"
 annotation = function *(s option)
 option = name [s] "=" [s] (literal / nmtoken / variable)
 
@@ -38,9 +32,7 @@ literal-char = %x0-5B         ; omit \
              / %xE000-10FFFF
 
 variable = "$" name
-function = ":" name
-markup-start = "+" name
-markup-end = "-" name
+function = (":" | "+" | "-") name
 
 name    = name-start *name-char ; matches XML https://www.w3.org/TR/xml/#NT-Name
 nmtoken = 1*name-char           ; matches XML https://www.w3.org/TR/xml/#NT-Nmtokens
diff --git a/spec/syntax.md b/spec/syntax.md
index 9fcb2daa0f..f99feb0509 100644
--- a/spec/syntax.md
+++ b/spec/syntax.md
@@ -7,9 +7,8 @@
    1. [Design Restrictions](#design-restrictions)
 1. [Overview & Examples](#overview--examples)
    1. [Messages](#messages)
-   1. [Placeholders](#placeholders)
+   1. [Expressions](#expressions)
    1. [Formatting Functions](#formatting-functions)
-   1. [Markup Elements](#markup-elements)
    1. [Selection](#selection)
    1. [Local Variables](#local-variables)
    1. [Complex Messages](#complex-messages)
@@ -19,9 +18,7 @@
    1. [Selectors](#selectors)
    1. [Variants](#variants)
    1. [Patterns](#patterns)
-   1. [Placeholders](#placeholders)
    1. [Expressions](#expressions)
-   1. [Markup](#markup)
 1. [Tokens](#tokens)
    1. [Keywords](#keywords)
    1. [Text and Literals](#text-and-literals)
@@ -49,7 +46,7 @@ The design goals of the syntax specification are as follows:
 
 1. The syntax inside translatable content should be easy to understand for humans.
    This includes making it clear which parts of the message body _are_ translatable content,
-   which parts inside it are placeholders,
+   which parts inside it are placeholders for expressions,
    as well as making the selection logic predictable and easy to reason about.
 
    - _Non-Goal_: Make the syntax intuitive enough for non-technical translators to hand-edit.
@@ -111,15 +108,15 @@ let hello = new MessageFormat('{Hello, world!}')
 hello.format()
 ```
 
-### Placeholders
+### Expressions
 
-A _placeholder_ represents a location in the _pattern_ that will be replaced
-in the formatted value (the output).
+An _expression_ represents a part of a message that will be determined
+during the message's formatting.
 
-A _placeholder_ appears within `{…}` delimiters. A _placeholder_ can only
-appear within a _pattern_ and can contain either an _expression_ or _markup_.
+An _expression_ always uses `{…}` delimiters.
+An _expression_ can appear as a local variable value, as a _selector_, and within a _pattern_.
 
-A simple _placeholder_ is simply a variable name:
+A simple _expression_ is a bare variable name:
 
     {Hello, {$userName}!}
 
@@ -144,33 +141,38 @@ plucking the first name from the object representing a person:
 
     {Hello, {$userObj :person firstName=long}!}
 
-### Markup Elements
+Functions use one of the following prefix sigils:
 
-_Markup_ is a set of _placeholders_ that can be replaced by runtime specific
-formatting or attributes applied to the _pattern_.
+- `:` for standalone content
+- `+` for starting or opening elements
+- `-` for ending or closing elements
 
-For example, a message with two markup-like element placeholders, `button` and `link`,
-which the runtime can use to construct a document tree structure for a UI framework.
+A message with two markup-like _functions_, `button` and `link`,
+which the runtime can use to construct a document tree structure for a UI framework:
 
     {{+button}Submit{-button} or {+link}cancel{-link}.}
 
+An opening element MAY be present in a message without a corresponding closing element,
+and vice versa.
+
 ### Selection
 
 A _selector_ selects a specific _pattern_ from a list of available _patterns_
-in a _message_ based on the values of _variables_ or _expressions_.
+in a _message_ based on the value of its _expression_.
+A message can have multiple selectors.
 
-A message with a single selector:
+A message with a single _selector_:
 
     match {$count :number}
     when 1 {You have one notification.}
     when * {You have {$count} notifications.}
 
-A message with a single selector which is an invocation of
+A message with a single _selector_ which is an invocation of
 a custom function `:platform`, formatted on a single line:
 
     match {:platform} when windows {Settings} when * {Preferences}
 
-A message with a single selector and a custom `:hasCase` function
+A message with a single _selector_ and a custom `:hasCase` function
 which allows the message to query for presence of grammatical cases required for each variant:
 
     match {$userName :hasCase}
@@ -178,7 +180,7 @@ which allows the message to query for presence of grammatical cases required for
     when accusative {Please welcome {$userName :person case=accusative}!}
     when * {Hello!}
 
-A message with 2 selectors:
+A message with 2 _selectors_:
 
     match {$photoCount :number} {$userGender :equals}
     when 1 masculine {{$userName} added a new photo to his album.}
@@ -190,9 +192,11 @@ A message with 2 selectors:
 
 ### Local Variables
 
-A _message_ can define local variables, such as might be needed for the transforming input or providing
-additional data to a _selector_ or _function_. Local variables appear in a _declaration_, which
-defines the value of a named local variable.
+A _message_ can define local variables,
+such as might be needed for transforming input
+or providing additional data to an _expression_.
+Local variables appear in a _declaration_,
+which defines the value of a named local variable.
 
 A _message_ containing a _declaration_ defining a local variable `$whom` which is then used twice inside the pattern:
 
@@ -211,9 +215,9 @@ A message defining two local variables:
 ### Complex Messages
 
 The various features can be used to produce arbitrarily complex messages by combining
-_declarations_, _selectors_, _functions_, _markup_ and more.
+_declarations_, _selectors_, _functions_, and more.
 
-A complex message with 2 selectors and 3 local variable definitions:
+A complex message with 2 _selectors_ and 3 local variable _declarations_:
 
     let $hostName = {$host :person firstName=long}
     let $guestName = {$guest :person firstName=long}
@@ -248,7 +252,7 @@ if it meets additional semantic requirements about its structure, defined below.
 ### Message
 
 A **_message_** is a (possibly empty) list of _declarations_ followed by either a single _pattern_,
-or a `match` statement containing one or more _variants_ which represent the translatable body of the message.
+or a `match` statement followed by one or more _variants_ which represent the translatable body of the message.
 
 A _message_ MUST be delimited with `{` at the start, and `}` at the end. Whitespace MAY
 appear outside the delimiters; such whitespace is ignored. No other content is permitted
@@ -267,17 +271,16 @@ within the scope of the message to the value of an expression.
 This local variable can then be used in other expressions within the same message.
 
 ```abnf
-declaration = let s variable [s] "=" [s] "{" [s] expression [s] "}"
+declaration = let s variable [s] "=" [s] expression
 ```
 
 ### Selectors
 
-A **_selector_** is a statement containing one or more expressions
+A `match` statement contains one or more **_selectors_**
 which will be used to choose one of the _variants_ during formatting.
 
 ```abnf
-selectors = match 1*([s] selector)
-selector = "{" [s] expression [s] "}"
+selectors = match 1*([s] expression)
 ```
 
 Examples:
@@ -298,7 +301,7 @@ when * {{$frac} apples}
 ### Variants
 
 A **_variant_** is a keyed _pattern_.
-The keys are used to match against the selector expressions defined in the `match` statement.
+The keys are used to match against the _selectors_ defined in the `match` statement.
 The key `*` is a "catch-all" key, matching all selector values.
 
 ```abnf
@@ -308,8 +311,8 @@ key = nmtoken / literal / "*"
 
 A _well-formed_ message is considered _valid_ if the following requirements are satisfied:
 
-- The number of keys on each variant MUST be equal to the number of selectors.
-- At least one variant's keys MUST all be equal to the catch-all key (`*`).
+- The number of keys on each _variant_ MUST be equal to the number of _selectors_.
+- At least one _variant's_ keys MUST all be equal to the catch-all key (`*`).
 
 ### Patterns
 
@@ -329,7 +332,7 @@ This serves 3 purposes:
   are translatable and which ones are part of the formatting logic definition.
 
 ```abnf
-pattern = "{" *(text / placeholder) "}"
+pattern = "{" *(text / expression) "}"
 ```
 
 Examples:
@@ -340,73 +343,59 @@ Examples:
 
 Whitespace within a _pattern_ is meaningful and MUST be preserved.
 
-### Placeholders
-
-A **_placeholder_** contains either an expression or a markup element.
-
-```abnf
-placeholder = "{" [s] expression [s] "}"
-            / "{" [s] markup-start *(s option) [s] "}"
-            / "{" [s] markup-end [s] "}"
-```
-
 ### Expressions
 
-**_Expressions_** can either start with an operand, or be standalone function calls.
+**_Expressions_** can either start with an operand or a function call.
 
 The operand is a literal or a variable name.
 The operand can be optionally followed by an _annotation_:
-a formatting function and its named options.
-Formatting functions do not accept any positional arguments
+a function and its named options.
+Functions do not accept any positional arguments
 other than the operand in front of them.
 
-Standalone function calls don't have any operands in front of them.
+Function calls do not require an operand as an argument,
+but an _expression_ must not be completely empty.
 
 ```abnf
-expression = ((literal / variable) [s annotation])
-           / annotation
+expression = "{" [s] (((literal / variable) [s annotation]) / annotation) [s] "}"
 annotation = function *(s option)
 option = name [s] "=" [s] (literal / nmtoken / variable)
 ```
 
-Examples:
+Expression examples:
 
 ```
-|1.23|
+{|1.23|}
 ```
 
 ```
-|1.23| :number maxFractionDigits=1
+{|1.23| :number maxFractionDigits=1}
 ```
 
 ```
-|Thu Jan 01 1970 14:37:00 GMT+0100 (CET)| :datetime weekday=long
+{|Thu Jan 01 1970 14:37:00 GMT+0100 (CET)| :datetime weekday=long}
 ```
 
 ```
-$when :datetime month=2-digit
+{$when :datetime month=2-digit}
 ```
 
 ```
-:message id=some_other_message
+{:message id=some_other_message}
 ```
 
-### Markup
-
-**_Markup elements_** (or just **_markup_**) provide a structured way to mark up parts of the content.
-There are two kinds of elements: start (opening) elements and end (closing) elements,
-each with its own syntax.
-They mimic XML elements, but do not require well-formedness.
-Standalone display elements should be represented as function expressions.
+```
+{+ssml.emphasis level=strong}
+```
 
-Examples:
+Message examples:
 
 ```
 {This is {+b}bold{-b}.}
 ```
 
 ```
-{{+h1 name=|above-and-beyond|}Above And Beyond{-h1}}
+{{+h1 name=above-and-beyond}Above And Beyond{-h1}}
 ```
 
 ## Tokens
@@ -455,8 +444,7 @@ literal-char = %x0-5B         ; omit \
 ### Names
 
 The _name_ token is used for variable names (prefixed with `$`),
-function names (prefixed with `:`),
-markup names (prefixed with `+` or `-`),
+function names (prefixed with `:`, `+` or `-`),
 as well as option names.
 A name MUST NOT start with an ASCII digit and certain basic combining characters.
 Otherwise, the set of characters allowed in names is large.
@@ -473,9 +461,7 @@ uses Nmtokens.
 
 ```abnf
 variable = "$" name
-function = ":" name
-markup-start = "+" name
-markup-end = "-" name
+function = (":" | "+" | "-") name
 ```
 
 ```abnf