How to work around Windows' restricted characters

The problem

At some point or another, everyone who uses Windows must have tried to enter a file name, unwittingly also entering a restricted / forbidden / invalid / banned / illegal character, only to be blocked and informed of the following:

A file name can’t contain any of the following characters:
\ / : * ? ” < > |

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Personally, I’ve always found it irritating to have such common punctuation disallowed.

The explanation

Basically, Windows blocks these characters from being used in file names because the same characters are used in its coding so it would get tripped up otherwise. Unix-based Operating Systems such as macOS also have forbidden characters for the same reason but they’re significantly fewer.

What many people don’t know is that Windows’ file names support the Unicode character set and it only blocks the ASCII printable character versions:

Symbol	Name	Hex code	Decimal code
\	Backslash	5C	92
/	Slash / divide	2F	47
:	Colon	3A	58
*	Asterisk	2A	42
?	Question mark	3F	63
"	Double quotes / speech marks	22	34
<	Less than / open angled bracket	3C	60
>	Greater than / close angled bracket	3E	62
|	Vertical bar / pipe	7C	124

So, what if you could find Unicode characters that look like the “original” characters but aren’t technically the same…? Spoiler: you can.

The workaround

Using https://unicode-search.net/unicode-namesearch.pl?term=, I have found Unicode characters that look like the original characters but aren’t the same so they can be used in Windows file names!

Symbol	Name	Unicode code
\	Reverse Solidus Operator	U+29F5
∕	Division Slash	U+2215
꞉	Modifier Letter Colon	U+A789
⁎	Low Asterisk	U+204E
？	Fullwidth Question Mark	U+FF1F
“	Left Double Quotation Mark	U+201C
”	Right Double Quotation Mark	U+201D
＜	Fullwidth Less-Than Sign	U+FF1C
＞	Fullwidth Greater-Than Sign	U+FF1E
⏐	Vertical Line Extension	U+23D0

So, how can you type these?

Edit: For a significantly better version of the below, I now use an AutoHotkey script which automatically replaces the characters when File Explorer windows are open so you don’t have to remember key combinations. This is available in my other blog post “Windows apps for an efficient workflow“.

Personally, I use AutoHotkey and the following custom script (.AHK file) so that all I have to do is press left Alt (LAlt) or right Alt (RAlt) and the normal key:

; Configuration
	#EscapeChar `

; Back slash (⧵)
	LAlt & \::SendInput {U+29F5}
	
; Forward slash (∕)
	LAlt & /::SendInput {U+2215}
	
; Colon (꞉)
	LAlt & `;::SendInput {U+A789}
	
; Asterisk (⁎)
	LAlt & 8::SendInput {U+204E}
	
; Question mark (？)
	RAlt & ?::SendInput {U+FF1F}
	
; Quotation / speech marks (“)
	RAlt & 2::SendInput {U+201C}
	
; Quotation / speech marks (”)
	LAlt & 2::SendInput {U+201D}

; Less than sign (＜)
	RAlt & <::SendInput {U+FF1C}

; Greater than sign (＞)
	RAlt & >::SendInput {U+FF1E}

; Vertical line (⏐)
	RAlt & |::SendInput {U+23D0}

; Date with Unicode thin spaces (U+2009) and forward slashes (U+2215)
	LAlt & d::
		FormatTime, Date,, yyyy ∕ MM ∕ dd
		SendInput, %Date%
	return
	
; Time with Unicode colons (U+A789)
	LAlt & t::
		FormatTime, Time,, HH꞉mm꞉ss
		SendInput, %Time%
	return

; Right arrow (→)
	LAlt & Right::SendInput {U+2192}

; Left arrow (←)
	LAlt & Left::SendInput {U+2190}

; Up arrow (↑)
	LAlt & Up::SendInput {U+2191}

; Down arrow (↓)
	LAlt & Down::SendInput {U+2193}

Below is a demonstration of this:

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I have been using these characters in file names ever since in Dropbox, OneDrive for Business, Microsoft Word, Adobe Reader, etc on Windows, iOS, and web and, as of 2020 ∕ 09 ∕ 10 (😉), I have experienced no compatibility problems.