I am trying to understand how to use Custom Indicators

[macpee]

I seldom worked with indicators as far as EA is concerned?
All I did was manually past indicators on charts when I need them even while working with EA.
This can be tasking when back testing the EA being designed.
What exactly is iCustom indicators?
Are they different from the indicators we manually paste on MT4 chart?
If no then why is it that (almost) every indicator has its iCustom equivalent?
I also think that iCustom indicators can be codded to add to MT4 chart by EA.
If so then what is the command to add the iCustom indicators to the chart by EA?

[Daniel Cioca]

macpee:
I seldom worked with indicators as far as EA is concerned?
All I did was manually past indicators on charts when I need them even while working with EA.
This can be tasking when back testing the EA being designed.
What exactly is iCustom indicators?
Are they different from the indicators we manually paste on MT4 chart?
If no then why is it that (almost) every indicator has its iCustom equivalent?
I also think that iCustom indicators can be codded to add to MT4 chart by EA.
If so then what is the command to add the iCustom indicators to the chart by EA?

If you check that link with iCustom indicators you will understand … this is how you call the indicators into you program … some of the indicators have designated functions for calling… like iATR… iMA… and many more… mostly indicators included in MT4 installation … all other indicators will use iCustom function to call indicator buffers… 

[Quinn]

Watch this video. I learned iCustoms from this and much more.

https://www.youtube.com/watch?v=9PfIfGzSHak

[William Roeder]

1. macpee: I seldom worked with indicators as far as EA is concerned?

   Don't try to do that. There are no buffers, no IndicatorCounted() or prev_calculated. No way to know if older bars have changed or been added (history update.)

   Just get the value(s) of the indicator(s) into EA/indicator (using iCustom) and do what you want with it.
             (MT4) Detailed explanation of iCustom - MQL4 programming forum (2017)

2. macpee: All I did was manually past indicators on charts when I need them even while working with EA.
   

   Code has no eyes; they don't need to see the indicator on the chart, just the values. If you want to see it, you add it to the appropriate chart.

3. macpee: What exactly is iCustom indicators?
   Are they different from the indicators we manually paste on MT4 chart?
   If no then why is it that (almost) every indicator has its iCustom equivalent?

   Any indicator that isn't built into the language. Technical Indicators - MQL4 Reference

   By definition, they must be different.
   

4. macpee: I also think that iCustom indicators can be codded to add to MT4 chart by EA.
   If so then what is the command to add the iCustom indicators to the chart by EA?

   There is no (and will not ever be) ChartIndicatorAdd in MT4.
             MQL4 Add indicator to chart from EA - MQL4 programming forum #18 (2016)

   use ChartApplyTemplate() or go down the rabbit hole.
             MQL4 Add indicator to chart from EA - MQL4 programming forum #1 (2016) and #27 (2018) and Issues with PostMessageW in MQL4 | Forex Factory #27 (2020)

[macpee]

DannyBass #:
If you check that link with iCustom indicators you will understand … this is how you call the indicators into you program … some of the indicators have designated functions for calling… like iATR… iMA… and many more… mostly indicators included in MT4 installation … all other indicators will use iCustom function to call indicator buffers… 

You did not get my question right.

[macpee]

William Roeder #:

1. Don't try to do that. There are no buffers, no IndicatorCounted() or prev_calculated. No way to know if older bars have changed or been added (history update.)

   Just get the value(s) of the indicator(s) into EA/indicator (using iCustom) and do what you want with it.
             (MT4) Detailed explanation of iCustom - MQL4 programming forum (2017)

2. Code has no eyes; they don't need to see the indicator on the chart, just the values. If you want to see it, you add it to the appropriate chart.

3. Any indicator that isn't built into the language. Technical Indicators - MQL4 Reference

   By definition, they must be different.
   

4. There is no (and will not ever be) ChartIndicatorAdd in MT4.
             MQL4 Add indicator to chart from EA - MQL4 programming forum #18 (2016)

   use ChartApplyTemplate() or go down the rabbit hole.
             MQL4 Add indicator to chart from EA - MQL4 programming forum #1 (2016) and #27 (2018) and Issues with PostMessageW in MQL4 | Forex Factory #27 (2020)

You got all my questions right. Unfortunately, your last answer (4) is a bitter pill I have to make do with in MT4/MQL4.