This is documentation for Mathematica 6, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.1)

Structural Elements and Keyboard Characters

full name
alias
\[InvisibleComma]Esc , Esc
\[InvisibleApplication]Esc @ Esc
\[InvisibleSpace]Esc is Esc
\[ImplicitPlus]Esc + Esc
full name
alias
\[AlignmentMarker]Esc am Esc
\[NoBreak]Esc nb Esc
\[Null]Esc null Esc

Invisible characters.

In the input there is an invisible comma between the 1 and 2.
In[1]:=
Click for copyable input
Out[1]=
Here there is an invisible space between the x and y, interpreted as multiplication.
In[2]:=
Click for copyable input
Out[2]//FullForm=
\[Null] does not display, but can take modifications such as superscripts.
In[3]:=
Click for copyable input
Out[3]=
The \[AlignmentMarker] does not display, but shows how to line up the elements of the column.
In[4]:=
Click for copyable input
Out[4]//DisplayForm=
The \[ImplicitPlus] operator is used as a hidden plus sign in mixed fractions.
In[5]:=
Click for copyable input
Out[5]=
full name
alias
\[VeryThinSpace]Esc Esc
\[ThinSpace]Esc Esc
\[MediumSpace]Esc Esc
\[ThickSpace]Esc Esc
\[InvisibleSpace]Esc is Esc
\[NewLine]
full name
alias
\[NegativeVeryThinSpace]Esc - Esc
\[NegativeThinSpace]Esc - Esc
\[NegativeMediumSpace]Esc - Esc
\[NegativeThickSpace]Esc - Esc
 \[NonBreakingSpace]Esc nbs Esc

\[IndentingNewLine]Esc nl Esc

Spacing and newline characters.

form
full name
alias
\[SelectionPlaceholder]Esc spl Esc
form
full name
alias
\[Placeholder]Esc pl Esc

Characters used in buttons.

In the buttons in a palette, you often want to set up a template with placeholders to indicate where expressions should be inserted. \[SelectionPlaceholder] marks the position where an expression that is currently selected should be inserted when the contents of the button are pasted. \[Placeholder] marks other positions where subsequent expressions can be inserted. The Tab key will take you from one such position to the next.
form
full name
alias
\[SpaceIndicator]Esc space Esc
\[ReturnIndicator]Esc ret Esc
\[ReturnKey]Esc ret Esc
\[EnterKey]Esc ent Esc
\[EscapeKey]Esc esc Esc
\[AliasIndicator]Esc esc Esc
form
full name
alias
\[RoundSpaceIndicator]
\[ControlKey]Esc ctrl Esc
\[CommandKey]Esc cmd Esc
\[LeftModified]Esc [ Esc
\[RightModified]Esc ] Esc
\[CloverLeaf]Esc cl Esc

Representations of keys on a keyboard.

In describing how to enter input into Mathematica, it is sometimes useful to give explicit representations for keys you should press. You can do this using characters like and . Note that and are actually treated as spacing characters by Mathematica.
This string shows how to type 2.
In[6]:=
Click for copyable input
Out[6]=

Characters generated in Mathematica output.

Mathematica uses a \[Continuation] character to indicate that the number continues onto the next line.
In[7]:=
Click for copyable input
Out[7]=

Raw keyboard characters.

The fonts that are distributed with Mathematica contain their own renderings of many ordinary keyboard characters. The reason for this is that standard system fonts often do not contain appropriate renderings. For example, ^ and ~ are often drawn small and above the centerline, while for clarity in Mathematica they must be drawn larger and centered on the centerline.