Protobuf syntax with colons - syntax

Question

Here are three examples of protobuf syntax.
mscoco_label_map.pbtxt
item {
name: "/m/01g317"
id: 1
display_name: "person"
}
item {
name: "/m/0199g"
id: 2
display_name: "bicycle"
}
...
en.wikipedia.org
anotherfield {
foo: 123
bar: 456
}
anotherfield {
foo: 222
bar: 333
}
Official documentation
syntax = "proto3";
message SearchRequest {
string query = 1;
int32 page_number = 2;
int32 result_per_page = 3;
}
Official (#3) example is obviously differs from #1 and #2. Did I miss a paragraph in official documentation which states that colon can be used instead of equal sign?
Official documentation describes a JSON Mapping, but there is not a single example that looks like #1 and #2. Also #1 and #2 is not a valid JSON either (missing quotes around keys, missing commas).
Q: where are #1 and #2 syntax came from?
Link to better (than official docs) syntax description is appreciated.

Answer 1

Thanks to Marc's Gravell response I was able to find out the answer.
#3 is a schema, proto syntax, think XSD (XML Schema Definition).
#1, #2 is a text dump of an actual data (payload), textproto syntax, *.pbtxt file extension, think XML or JSON.
Related question: What does the protobuf text format look like?
Related links:
https://developers.google.com/protocol-buffers/docs/reference/cpp/google.protobuf.text_format
C++ API for printing and parsing protocol messages in a human-readable, text-based format.
https://googleapis.dev/python/protobuf/latest/google/protobuf/text_format.html
Python API
https://developers.google.com/protocol-buffers/docs/reference/proto3-spec
Protocol Buffers Version 3 Language Specification
https://github.com/protocolbuffers/protobuf/blob/master/src/google/protobuf/text_format.cc#L288
Source code (C++) of text format ASCII representation parser.
https://medium.com/#nathantnorth/protocol-buffers-text-format-14e0584f70a5
Protocol Buffers: Text Format (2019-10-11, Nathan North)
There are a couple different ways to structure the data (instead of using brackets, you could use <>) but unfortunately nothing in this realm is terribly well documented so it’s more of a game of try it and see if it works.
https://gist.github.com/henridf/704c1c812f04a502c1c26f77a739090b
Encoding a protobuf with protoc --encode (syntax example).
Clear syntax documentation of protobuf text format is still missing.