Extron electronic SFI244 Series, IPL T SF24 URL encoding, Reserved characters, Unsafe characters

Communication and Control, cont’d

Figure 4-31b — Browser view

URL encoding

URL encoding is the method of using ASCII hexadecimal characters to display specific characters in a URL. URL encoding is used for several reasons. On some operating systems, certain characters are unsafe or not available, and others are reserved by the HTML or URL specification. URL encoding is used to insure compatibility and functionality with most Internet browsers. As a general rule, use the hexadecimal encoding method shown below when these characters appear in your URLs.

The following types of characters do not require encoding in a URL:

Reserved characters

Reserved characters should not be encoded when they appear in their conventional meaning in a URL. For example, do not encode the slash (/) when using it as part of the URL syntax. Only encode unsafe characters (defined below) in your URLs.

The following table lists reserved characters.

	Characters	Hex	Dec
$	Dollar	24	36
&	Ampersand	26	38
+	Plus	2B	43
,	Comma	2C	44
/	Forward Slash / Virgule	2F	47
:	Colon	3A	58
;	Semi-colon	3B	59
=	Equal	3D	61
?	Question Mark	3F	63
@	“At” Symbol	40	64

Unsafe characters

URLs use some characters for “special use” in defining their syntax and these characters should be encoded. For various reasons, these characters present the possibility of being misunderstood within a URL.

The following table lists unsafe characters.

	Characters	Hex	Dec
	Space	20	32
" "	Quotation Marks	22	34
<	“Less Than” Symbol	3C	60
>	“Greater Than” Symbol	3E	62
#	Pound	23	35
%	Percent	25	37
Miscellaneous Characters

alphanumerics

special characters

reserved characters

0-9 a-z A-Z

$ _ _ . + ! * ( ) ,

; / ? : @ = &

When used for their reserved purposes, these characters do not require encoding within a URL.

{	Left Curly Brace	7B	123
}	Right Curly Brace	7D	125
	Vertical Bar / Pipe	7C	124
\	Backslash	5C	92
^	Caret	5E	94
~	Tilde	7E	126
[	Left Square Bracket	5B	91
]	Right Square Bracket	5D	93
`	Grave Accent	60	96

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