# Options for Expression Input and Output

option | typical default value | |

AutoIndent | Automatic | whether to indent after an explicit Return character is entered |

DelimiterFlashTime | 0.3 | the time in seconds to flash a delimiter when a matching one is entered |

ShowAutoStyles | True | whether to show automatic style variations for syntactic and other constructs |

ShowCursorTracker | True | whether an elliptical spot should appear momentarily to guide the eye if the cursor position jumps |

ShowSpecialCharacters | True | whether to replace by a special character as soon as the is entered |

ShowStringCharacters | True | whether to display when a string is entered |

SingleLetterItalics | False | whether to put single-letter symbol names in italics |

ZeroWidthTimes | False | whether to represent multiplication by a zero width character |

InputAliases | {} | additional name aliases to allow |

InputAutoReplacements | {"->"->"→",...} | strings to automatically replace on input |

AutoItalicWords | {"Mathematica",...} | words to automatically put in italics |

LanguageCategory | "NaturalLanguage" | what category of language to assume a cell contains for spell checking and hyphenation |

Options associated with the interactive entering of expressions.

The option SingleLetterItalics is typically set whenever a cell uses TraditionalForm.

Built into *Mathematica* are a large number of aliases for common special characters. InputAliases allows you to add your own aliases for further special characters or for any other kind of *Mathematica* input. A rule of the form "name"->expr specifies that should immediately be replaced on input by expr.

Aliases are delimited by explicit Esc characters. The option InputAutoReplacements allows you to specify that certain kinds of input sequences should be immediately replaced even when they have no explicit delimiters. By default, for example, is immediately replaced by . You can give a rule of the form to specify that whenever seq appears as a token in your input, it should immediately be replaced by rhs.

"NaturalLanguage" | human natural language such as English |

"Mathematica" | Mathematica input |

"Formula" | mathematical formula |

None | do no spell checking or hyphenation |

Settings for LanguageCategory to control spell checking and hyphenation.

The option LanguageCategory allows you to tell *Mathematica* what type of contents it should assume cells have. This determines how spelling and structure should be checked, and how hyphenation should be done.

option | typical default value | |

StructuredSelection | False | whether to allow only complete subexpressions to be selected |

DragAndDrop | False | whether to allow drag-and-drop editing |

Options associated with interactive manipulation of expressions.

*Mathematica* normally allows you to select any part of an expression that you see on the screen. Occasionally, however, you may find it useful to get *Mathematica* to allow only selections which correspond to complete subexpressions. You can do this by setting the option StructuredSelection->True.

Unlike most of the other options here, the DragAndDrop option can only be set for the entire front end, rather than for individual cells or cell styles.

GridBox[data,opts] | give options that apply to a particular grid box |

StyleBox[boxes,opts] | give options that apply to all boxes in boxes |

Cell[contents,opts] | give options that apply to all boxes in contents |

Cell[contents,GridBoxOptions->opts] | give default options settings for all GridBox objects in contents |

Examples of specifying options for the display of expressions.

As discussed in "Textual Input and Output", *Mathematica* provides many options for specifying how expressions should be displayed. By using StyleBox[boxes, opts] you can apply such options to collections of boxes. But *Mathematica* is set up so that any option that you can give to a StyleBox can also be given to a complete Cell object, or even a complete Notebook. Thus, for example, options like Background and LineIndent can be given to complete cells as well as to individual StyleBox objects.

There are some options that apply only to a particular type of box, such as GridBox. Usually these options are best given separately in each GridBox where they are needed. But sometimes you may want to specify default settings to be inherited by all GridBox objects that appear in a particular cell. You can do this by giving these default settings as the value of the option for the whole cell.

For most box types named , *Mathematica* provides a cell option that allows you to specify the default options settings for that type of box. Box types which take options can also have their options set in a stylesheet by defining the style. The stylesheets which come with *Mathematica* define many such styles.