user11529: Could we rename Processing (the language) tag to Processing-lang, and merge signal- and text-processing tags to data-processing tag. 

user7174: What does data-processing mean?
Although it's clear what processing refers to -- and I agree with renaming that tag to clarify that it's about the processing language itself; tag signal-processing and tag text-processing don't have any usage guidance. I'm leery of combining two already ill-defined groups of questions into another even less-well-defined group.
I took a look at the existing tagged questions, there's currently 25 questions tagged signal-processing and 9 questions tagged text-processing.
I can guess that signal-processing would include digital signal processing techniques (within the Arduino's capability), as well as analog filtering.
Browsing the 9 questions tagged text-processing, it's not clear to me what this tag actually means.

how an Arduino program(sketch) deals with strings of text input and output?
how the C pre-processor processes the text of the source code?
how the Arduino-specific language elements work?

Is program-got-so-many-errors-about-expected-or-before-either really about text processing? Seems like this question turned out to be about why #define dw 8; should not have the semicolon.  Similarly arduino-program-got-error-expected-primary-expression-before-token-error doesn't contain anything that looks to me like text processing. 
What about this question about F() FlashStringHelper -- that's useful and related to how constant string expressions are stored in an arduino program, but probably belongs in string instead.
And for that matter, why isn't How do I split an incoming string in text-processing when How to get string parts from string is? I'd edit it myself if I was sure what belonged in that tag.
So since text-processing has only 9 questions, and 0 followers, and it's unclear how these questions are related, let's instead:

rename processing to processing-lang as proposed by @Avamander
shore up signal-processing with a clear tag wiki definition
dispatch the 9 questions in text-processing to wherever they really belong (maybe string), then burninate text-processing.
add [text] as a synonym for string

Re-tagging individual questions is a straightforward edit, but without a clear well-defined definition of what the tag is supposed to mean, it's harder to find related stuff. 

11529: <p>Could we rename Processing (the language) tag to Processing-lang, and merge signal- and text-processing tags to data-processing tag. </p>
 7174: <p>What does data-processing mean?</p>

<p>Although it's clear what <a href="https://arduino.stackexchange.com/questions/tagged/processing" class="post-tag" title="show questions tagged &#39;processing&#39;" rel="tag">processing</a> refers to -- and I agree with renaming that tag to clarify that it's about the <em>processing language</em> itself; tag <a href="https://arduino.stackexchange.com/questions/tagged/signal-processing" class="post-tag" title="show questions tagged &#39;signal-processing&#39;" rel="tag">signal-processing</a> and tag <a href="https://arduino.stackexchange.com/questions/tagged/text-processing" class="post-tag" title="show questions tagged &#39;text-processing&#39;" rel="tag">text-processing</a> don't have any usage guidance. I'm leery of combining two already ill-defined groups of questions into another even less-well-defined group.</p>

<p>I took a look at the existing tagged questions, there's currently 25 questions tagged <a href="https://arduino.stackexchange.com/questions/tagged/signal-processing?sort=votes&amp;pagesize=50">signal-processing</a> and 9 questions tagged <a href="https://arduino.stackexchange.com/questions/tagged/text-processing?sort=votes&amp;pageSize=15">text-processing</a>.</p>

<p>I can guess that <a href="https://arduino.stackexchange.com/questions/tagged/signal-processing" class="post-tag" title="show questions tagged &#39;signal-processing&#39;" rel="tag">signal-processing</a> would include digital signal processing techniques (within the Arduino's capability), as well as analog filtering.</p>

<p>Browsing the 9 questions tagged <a href="https://arduino.stackexchange.com/questions/tagged/text-processing?sort=votes&amp;pageSize=15">text-processing</a>, it's not clear to me what this tag actually means.</p>

<ul>
<li>how an Arduino program(sketch) deals with strings of text input and output?</li>
<li>how the C pre-processor processes the text of the source code?</li>
<li>how the Arduino-specific language elements work?</li>
</ul>

<p>Is <a href="https://arduino.stackexchange.com/questions/6660/program-got-so-many-errors-about-expected-or-before-either">program-got-so-many-errors-about-expected-or-before-either</a> really about text processing? Seems like this question turned out to be about why <code>#define dw 8;</code> should not have the semicolon.  Similarly <a href="https://arduino.stackexchange.com/questions/8470/arduino-program-got-error-expected-primary-expression-before-token-error">arduino-program-got-error-expected-primary-expression-before-token-error</a> doesn't contain anything that looks to me like text processing. </p>

<p>What about this question about <a href="https://arduino.stackexchange.com/questions/17774/any-way-to-use-f-macro-with-a-passed-variable">F() FlashStringHelper</a> -- that's useful and related to how constant string expressions are stored in an arduino program, but probably belongs in <a href="https://arduino.stackexchange.com/questions/tagged/string" class="post-tag" title="show questions tagged &#39;string&#39;" rel="tag">string</a> instead.</p>

<p>And for that matter, why <em>isn't</em> <a href="https://arduino.stackexchange.com/questions/1013/how-do-i-split-an-incoming-string">How do I split an incoming string</a> in text-processing when <a href="https://arduino.stackexchange.com/questions/10557/how-to-get-string-parts-from-string">How to get string parts from string</a> is? I'd edit it myself if I was sure what belonged in that tag.</p>

<p>So since <a href="https://arduino.stackexchange.com/questions/tagged/text-processing" class="post-tag" title="show questions tagged &#39;text-processing&#39;" rel="tag">text-processing</a> has only 9 questions, and 0 followers, and it's unclear how these questions are related, let's instead:</p>

<ol>
<li>rename <a href="https://arduino.stackexchange.com/questions/tagged/processing" class="post-tag" title="show questions tagged &#39;processing&#39;" rel="tag">processing</a> to processing-lang as proposed by @Avamander</li>
<li>shore up <a href="https://arduino.stackexchange.com/questions/tagged/signal-processing" class="post-tag" title="show questions tagged &#39;signal-processing&#39;" rel="tag">signal-processing</a> with a clear tag wiki definition</li>
<li>dispatch the 9 questions in <a href="https://arduino.stackexchange.com/questions/tagged/text-processing" class="post-tag" title="show questions tagged &#39;text-processing&#39;" rel="tag">text-processing</a> to wherever they really belong (maybe <a href="https://arduino.stackexchange.com/questions/tagged/string" class="post-tag" title="show questions tagged &#39;string&#39;" rel="tag">string</a>), then burninate <a href="https://arduino.stackexchange.com/questions/tagged/text-processing" class="post-tag" title="show questions tagged &#39;text-processing&#39;" rel="tag">text-processing</a>.</li>
<li>add [text] as a synonym for <a href="https://arduino.stackexchange.com/questions/tagged/string" class="post-tag" title="show questions tagged &#39;string&#39;" rel="tag">string</a></li>
</ol>

<p>Re-tagging individual questions is a straightforward edit, but without a clear well-defined definition of what the tag is supposed to mean, it's harder to find related stuff. </p>
