Reference: https://docs.splunk.com/Documentation/Splunk/8.0.3/Knowledge/Usesearchmacros The correct way to execute the macro in a search string is to use the format macro_name($arg1$, $arg2$,
...) where $arg1$, $arg2$, etc. are the arguments for the macro. In this case, the macro name is convert_sales and it takes three arguments: currency, symbol, and rate. The arguments are enclosed in dollar signs and separated by commas. Therefore, the correct way to execute the macro is convert_sales ($euro$, $€$, .79).

There are several ways to access the field extractor. The option that automatically identifies data type, source type, and sample event is Fields sidebar > Extract New Field. The field extractor is a tool that helps you extract fields from your data using delimiters or regular expressions. The field extractor can generate a regex for you based on your selection of sample values or you can enter your own regex in the field extractor. The field extractor can be accessed by using various methods, such as:
Fields sidebar > Extract New Field: This is the easiest way to access the field extractor. The fields sidebar is a panel that shows all available fields for your data and their values. When you click on Extract New Field in the fields sidebar, Splunk will automatically identify the data type, source type, and sample event for your data based on your current search criteria. You can then use the field extractor to select sample values and generate a regex for your new field.
Event Actions > Extract Fields: This is another way to access the field extractor. Event actions are actions that you can perform on individual events in your search results, such as viewing event details, adding to report, adding to dashboard, etc. When you click on Extract Fields in the event actions menu, Splunk will use the current event as the sample event for your data and ask you to select the source type and data type for your data. You can then use the field extractor to select sample values and generate a regex for your new field.
Settings > Field Extractions > New Field Extraction: This is a more advanced way to access the field extractor. Settings is a menu that allows you to configure various aspects of Splunk, such as indexes, inputs, outputs, users, roles, apps, etc. When you click on New Field Extraction in the Settings menu, Splunk will ask you to enter all the details for your new field extraction manually, such as app context, name, source type, data type, sample event, regex, etc. You can then use the field extractor to verify or modify your regex for your new field.

https://docs.splunk.com/Documentation/Splunk/8.1.0/SearchReference/ConversionFunctions#tostring.28X.
2CY.29
The tostring function in the eval command converts a numeric value to a string value. It can take an optional second argument that specifies the format of the string value. Some of the possible formats are:
* hex: converts the numeric value to a hexadecimal string.
* commas: adds commas to separate thousands in the numeric value.
* duration: converts the numeric value to a human-readable duration string, such as "2h 3m 4s".
Therefore, the formats A, B, and D can be used with the tostring function.