If you follow me on social media, you probably already know that I have written a book about ABAP in Eclipse. The full title is: ABAP in Eclipse - Install, Configure, Use, and Enhance Your ADT and it is pointed to all ADT users as it covers the topics from installation up to extension of Eclipse. If you have the book, let me know your feedback, as this is most important for an author to see where he did well and where he need to still learn.

Cheers 

Column ID is not really a special field in ALV. It is always filled automatically by ALV and your manual entries are overwritten and set to the same value as COL_POS (Column position).

I’ve prepared a demo program (ZDEMO_AIN_CL46) to show you, how the COL_ID is changing on a base of COL_POS. On the selection screen you can find two radio-buttons.
 

Figure 120 ZDEMO_AIN_CL46 Selection screen

When you select the first option - “COL_ID filled”,  the FCAT will be created with manual COL_ID.
 

I was trying to find an usage of this field in ALV, but I failed. Any of known behaviours of ALV didn’t shown anything on a base of this field.

Hotspot fields are very widely used in ALV, such fields have the behaviour and style of hyperlinks, which means they are triggering the single-click event of ALV called HOTSPOT_CLICK. It is commonly used to show the details of the clicked object, or to move to a transaction in which the object can be modified.

As you can imagine, setting column as a HOTSPOT is very easy, you need to pass only the ABAP_TRUE (‘X’) value to the field catalog, but this will only change the style of the field (content of the field is underlined) and it will fire the HOTSPOT_CLICK event.

Figure 114 Setting column as hotspot

Group key is not widely used but it has nice feature. Once you group the field catalog fields and you pass the group name into parameter IT_SPECIAL_GROUPS of method SET_TABLE_FOR_FIRST_DISPLAY, then in selection of fields to display in layout change window, you’ll be able to choose to see all hidden fields or the hidden fields from the group you’ve created. If you don’t pass the group name into IT_SPECIAL_GROUPS, then this setting of field catalog has no impact on display.

For my demo program ZDEMO_AIN_CL43, I’ve created a field catalog with REF_TABLE filled for all fields, so it is easier to understand the functionality. Additionally, I’ve hidden all fields that have SP_GROUP filled, so you can check the behaviour directly after running the program.

Figure 109 Field catalog with Group Keys

You may suspect that setting up a domain name in the field catalog will make some effect on the display, for example in data type, length, lowercase sign,  but it seems that it has no effect in ALV grid. Maybe just for information and for Report-Report interface, where this field is use as one of the matching criteria for selection-screen parameters.

As you can see on the next image, although I gave the DOMNAME value FLAG, it didn’t changed anything in the field catalog.

Figure 108 DOMNAME in Field catalog

Before writing this part, I was never using Report-Report Interface, so probably it is not common scenario to do so, or it is not used with the systems I had possibility to use. But anyway I’ve made a deep dive into topic, to understand how we can use this interface and for which purpose.  

Seems that, using this interface, you can call from ALV grid an BW Query, SAP Query, ABAP Report Program or Transaction. Probably depending on the installed version of your system, or addons, the list of the interfaces may be longer.

Anyway I’ve focused here on a simple example of calling another ABAP report using RRI. At the beginning I was wondering if configuration in table TRSTI and setting the parameter REPREP to ABAP_TRUE will be enough to call the interface. So I’ve started with filling TRSTI, where I’ve set sender and receiver, both as RT (ABAP Report Program).

Figure 100 TRSTI entry for sender program

This field allows us to set (or change) the header text of the column. It can consist up to 55 characters in lowercase mode. When you use data dictionary reference ( REF_FIELD, REF_TABLE ) it is populated automatically from the data element of the referenced field.

Figure 97 Texts of Data Element S_FROMAIRP

The changes of this parameter are only visible in edit mode and makes sense only for character or string fields. If it is set to ABAP_TRUE (‘X’), then the ALV grid stores in internal table the value in lowercase, if the value of the parameter is empty, then it will always convert the entered value to uppercase.

Figure 96 Results of zdemo_ain_cl39 with lowercase turned on

As the description says, the meaning of that field is to set the internal length of the field in Bytes. During my whole career as ABAP Developer, I had never filled that field manually. Usually you’ll not bother yourself about it. But if you do, then take into consideration following information:

• Length is in Bytes, so remember that it doesn’t mean, that one character takes one Byte
• In display mode, you’ll not notice probably any change
• When you’ll setup this incorrectly, you may have problems when you allow grid to be editable, for example:
  When I’ve set the INTLEN to ‘2’ for column FLTIME, then although I’ve entered the value of ‘12’ into the column, system didn’t allowed me to save it.

Figure 94 Error in edit mode caused by wrong value of field INTLEN (ZDEMO_AIN_CL38)

Figure 95 Error message of  ZDEMO_AIN_CL38