Use Data Type in the Field proper to use Best Practice ?

[PROBERT68]

I am seeking information about how to add field in any shapefile that has no 

"The selected field is an inherent field of the feature class managed by the geodatabase. For example, in a polygon feature class, there are four fields that are unavailable for editing: OBJECTID, Shape, SHAPE_LENGTH, and SHAPE_AREA."

For example, If you have a polygon that shows grassland and it doesn't have the field it needs to calculate geomtery such as an acre.

Is there a website that explains for polygon, lines, points, etc that an user can decide to select which one ifor a proper field.

I have seen this site but it doesn't really help me much.

https://desktop.arcgis.com/en/arcmap/10.3/manage-data/geodatabases/arcgis-field-data-types.htm

Let me know if you need an clarification here.

[DanPatterson]

Calculate Geometry Attributes (Data Management)—ArcGIS Pro | Documentation

You can calculate geometry types and properties in the units you want using the above

[PROBERT68]

@DanPatterson   Yes I have seen this ...but it is another topic. I have been google but with no luck. I will post  it when I find it what I am looking for. 

[DanPatterson]

geometry uses is a floating point representation (eg it has a decimal place).  If you want to calculate acreage, then the field should be of that type (float, double), double will suffice for most purposes since I think memory is not an issue.

ArcGIS field data types—ArcGIS Pro | Documentation

explains the field types, their use and their representation in various types of databases

[PROBERT68]

One thing I didn't know is that when I got some many shapefiles from a field crew and they use GPS  . They were doing their  GSPing  to do fuel treatment and when I got them they were in WGS84. If you try to calculate them in acres ( They are in polygons ). I had trouble getting them and that is when I found out that they are in WGS84 and it needs to be in Projection Coordinate System in order to calculate them. So, I didn't know which data type to assign them in polygons. It is a fuel treatment and not sure which they prefer to use in square meters, square feet, Square inches and so on. 

So everyone from many different fields or background have their own prefer to use.  

Here is an example 

https://www.gislounge.com/calculating-polygon-area-in-arcmap/

If you go scroll way down very end, there is a  video showing how to calculate Kentucky counties and that state prefers square miles.

So I was just looking for something to get information. I think it might be hard for me to explain.... 

[DanPatterson]

well with the tool I suggested, you could calculate area multiple times in multiple units or pick one and have a conversion chart if someone wants units in another unit

Conversion Calculator

You can't please everyone all the time

[PROBERT68]

Thanks for the link.

Yeah.. 

Maybe one day I will find out then.