Update mention of proj-strings following #808

Author: Robinlovelace

07-reproj.Rmd

@@ -113,9 +113,10 @@ sf::st_crs("urn:ogc:def:crs:EPSG::4326")
 WKT strings are exhaustive, detailed, and precise, allowing for unambiguous CRSs storage and transformations.
 They contain all relevant information about any given CRS, including its datum and ellipsoid, prime meridian, projection, and units.^[
 Before the emergence of WKT CRS definitions, proj-string was the standard way to specify coordinate operations and store CRSs.
-These string representations, built on a key=value form (e.g, `+proj=longlat +datum=WGS84 +no_defs`), are, however, currently discouraged in most cases.
-PROJ version 6 and further still allows to use proj-strings to define coordinate operations, but some proj-string keys are no longer supported or are not advisable to use (e.g., `+nadgrids`, `+towgs84`, `+k`, `+init=epsg:`) and only three datums (i.e., WGS84, NAD83, and NAD27) can be directly set in proj-string.
-Importantly, proj-strings are not used to store CRSs anymore.
+These string representations, built on a key=value form (e.g, `+proj=longlat +datum=WGS84 +no_defs`), have already been, or should in the future be, superseded by WKT representations in most cases.
+
+Recent PROJ versions (6+) still allow use of proj-strings to define coordinate operations, but some proj-string keys are either no longer supported.
+<!-- `proj=`, `+nadgrids`, `+towgs84`, `+k`, `+init=epsg:` keys and only three datums (i.e., WGS84, NAD83, and NAD27) can be directly set in proj-string. -->
 Longer explanations of the evolution of CRS definitions and the PROJ library can be found in @bivand_progress_2021, Chapter 2 of @pebesma_spatial_2022, and [blog post by Floris Vanderhaeghe](https://inbo.github.io/tutorials/tutorials/spatial_crs_coding/).
 As outlined in the [PROJ documentation](https://proj.org/development/reference/cpp/cpp_general.html) there are different versions of the WKT CRS format including WKT1 and two variants of WKT2, the latter of which (WKT2, 2018 specification) corresponds to the ISO 19111:2019 [@opengeospatialconsortium_wellknown_2019].
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