All have a start and end, and use curly brackets.  Some take additional parameters separated by colons. :

They are also processed in this order of sequence as listed here:\\

Encrypts the inner data in DES format.
{{{
encrypt_start
}}}
URL encodes the inner data.
{{{
encode_start
}}}
URL decodes the inner data.
{{{
decode_start
}}}
Converts the inner data to uppercase.
{{{
upper_start
}}}
Converts the inner data to lowercase.
{{{
lower_start
}}}
Creates a MD5 hash of the inner data.
{{{
md5_start
}}}
Cuts off the last part of a path string in the inner data.  So /folder1/folder2/folder3/ would become /folder1/folder2/
{{{
chop_start
}}}
Cleans up HTML data to remove its tags with a regex expression.
{{{
htmlclean_start
}}}
Cleans up HTML data to remove tags using a different non regex algorithm.
{{{
htmlclean2_start
}}}
Gets the last element of a path in the inner data.  Example: {last_start}/folder1/folder2/file.txt{last_end} results in file.txt
{{{
last_start
}}}
Trims off white space on the ends of the inner data.
{{{
trim_start 
}}}
Safeguards the text for raw SQL preventing ' and ; and %, etc risks in input text.
{{{
sql_start
}}}
Finds a location of a string.  Example: {indexof_start:thing:-1}something to search in{indexof_end}    it searches for the location of 'thing' in that text starting from the right side moving backwards.  The -1 means a negative search, where a -5 would mean a negative search starting from position 5.  A 0 would mean start at the beginning.
{{{
indexof_start
}}}
Grab a part of a string.  Example:  {substring_start:2:5}something to find{substring_end}   would result in 'met'
\\Example_2:  {substring_start:-4:-1}something to find{substring_end}  would result in 'find'
\\The -4 is 4 from the end, and the -1 means all the way to the end. If you did a positive 1 it would do 1 character from the 4th character to the end.
{{{
substring_start
}}}
Split a string into pieces with the character(s) specified.  Example:  {split_start:_:3}this_is_a_test_for_split{split_end}  would result in the 3rd item which is the word 'test'
{{{
split_start
}}}
Change a part of the string.  Example: {replace_start:test:big_test}this_is_a_test_for_replace{replace_end}
{{{
replace_start
}}}
Add one to the value assumed to be an integer.  {increment_start}50{increment_end}   results in a value of 51.
{{{
increment_start
}}}
Opposite of increment.
{{{
decrement_start
}}}
Add an amount to the number.  Example:  {add_start:500}1000{add_end} results in 1500.
{{{
add_start
}}}
Parsing a date to a millisecond value.  Example: {parse_start:MMddyy HH~..~mm~..~ss}042578 22:43:12{parse_end}   Note how the sideways colon is used to represent the colon since colon is our separator character.  ~..~ means : in functions where that scenario occurs.
{{{
parse_start
}}}
Do the opposite, producing a formatted date.  {rparse_start:MMddyy HH~..~mm~..~ss}12345678923{rparse_end}  would result in some date formatted value.
{{{
rparse_start
}}}
Grab a part of a formatted URL.  Example:  {url_start:host}ftp://demo:demo@crushftp.com/demo/folder/file.txt{url_end}   would result in 'crushftp.com'. Valid items:
protocol,user,pass,host,port,path,file,query, in this order.
{{{
url_start
}}}
Get the length of the inner data.  Example: {length_start}blah{length_end}  would result in 4.
{{{
length_start
}}}
Do very basic math operation on text formatted math.  Example:  {math_start:l}5+5{math_end}  would result in 10.  The l is for LONG.  f is for FLOAT.  i is for INTEGER, which is the default.  So {math_start:f}5+5{math_end}  would result in 10.0
{{{
math_start
}}}
Reference a list of user attributes, separated by a delimitator character, of a group of users. Example: {group_start:email:MainUsers:,}Mygroup{group_end} comma separated list of user e-mail addresses members of Mygroup from MainUsers connection group
{{{
group_start
}}}
Trace geographically an IP using https://freegeoip.net, for example {geoip_start}{user_ip}{geoip_end} in a user task
{{{
geoip_start
}}}
Turn off function replacement. If the text start with the variable {ignore_functions} function replacement will be turned off.
{{{
ignore_functions
}}} 

__IMPORTANT:__ in case need to split on, replace or get substring position from the __:__(colon) character, will need to quote it like __~..~__, since it is also the separator between function arguments, where it is the case.