Understand devtools::check() warning notes

[RayStick]

domain_mapping: no visible binding for global variable ‘Note’
  Undefined global functions or variables:
    Note

When @BatoolMM added at the top:

utils::globalVariables(c("Note"))

the warning stopped

[RayStick]

Running devtools::check() on latest release (1.0.0) gives:

❯ checking for hidden files and directories ... NOTE
Found the following hidden files and directories:
.all-contributorsrc
These were most likely included in error. See section ‘Package
structure’ in the ‘Writing R Extensions’ manual.

❯ checking DESCRIPTION meta-information ... NOTE
Malformed Description field: should contain one or more complete sentences.

❯ checking top-level files ... NOTE
Non-standard files/directories found at top level:
‘CITATION.cff’ ‘CONTRIBUTING.md’ ‘data-raw’

❯ checking package subdirectories ... NOTE
Found the following CITATION file in a non-standard place:
CITATION.cff
Most likely ‘inst/CITATION’ should be used instead.

❯ checking R code for possible problems ... NOTE
compare_csv_outputs: no visible binding for global variable
‘MetaDataVersion’
compare_csv_outputs: no visible binding for global variable
‘MetaDataLastUpdated’
compare_csv_outputs: no visible binding for global variable
‘DomainListDesc’
compare_csv_outputs: no visible binding for global variable ‘Dataset’
compare_csv_outputs: no visible binding for global variable ‘Table’
compare_csv_outputs: no visible binding for global variable
‘DataElement’
domain_mapping: no visible binding for global variable ‘Note’
Undefined global functions or variables:
DataElement Dataset DomainListDesc MetaDataLastUpdated
MetaDataVersion Note Table

It would be good to understand these better, as it seems I may be declaring/handling variables in R in a sub-optimal way