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Hint: Three defaults decide what you get: which analysis, how much detail per path, and how many paths per group.

With no options, -path_delay is max (setup), -format is full, and one path is reported per path group. Paths are grouped by the clock that captures them, with separate groups for unclocked and unconstrained paths. OpenSTA reference

Hint: In a timing tool, min and max name the two analyses, not the size of anything.

min uses the earliest arrivals, which are checked against hold requirements; max uses the latest arrivals, checked against setup. OpenSTA reference

Hint: Read it as min plus max: the two analyses in one report.

min_max runs both analyses in one report: the setup (max) paths and the hold (min) paths. OpenSTA reference

Hint: There are two counts in this command: one per path group, one per endpoint. This is the first.

The default is 1 per group. Because -endpoint_path_count defaults to 1, each endpoint contributes at most one path, so these are the 10 worst endpoints of each group. OpenSTA reference

Hint: The group count caps the whole group; the endpoint count only decides how those paths may be shared out.

-group_path_count caps the paths per group; -endpoint_path_count caps how many of them may end at the same endpoint. Many of those paths can differ only in rise and fall edges; -unique_paths_to_endpoint keeps one path per set of pins. OpenSTA reference

Hint: The end of a path is its endpoint, and the format keeps only that.

The end format drops the stage-by-stage detail and keeps one line per path end: required time, arrival, and slack. It is the usual way to see how many endpoints fail and by how much. OpenSTA reference

Hint: The default report compresses each clock into a single `clock network delay` line. Ask what expanding it shows.

The default full format shows the clock network delay as a single line. full_clock expands it into the clock buffers on both sides, which shows where skew comes from. full_clock_expanded also shows the path from a generated clock's source. OpenSTA reference

Hint: Fields add columns to each stage; they do not filter which paths are reported.

The extra columns explain a slow stage: a large load, a high fanout, or a slow input slew. input_pin and net add the input pins and the nets as rows. OpenSTA reference

Hint: Read `-slack_max` as an upper bound on the slack of the paths you want listed.

-slack_max keeps paths with less slack than the value, and -slack_min keeps paths with more. Together with a large path count, -slack_max 0 lists the failing paths. OpenSTA reference

Hint: `-from`, `-through`, and `-to` mean here what they mean in a timing exception.

-from, -through, and -to narrow the report the same way they narrow a timing exception: from start points, through intermediate pins, to endpoints. OpenSTA reference

Hint: A path with no requirement has no slack, so ask where such paths are normally put.

They are reported in their own group. Without this option the unconstrained group is not reported at all. An unconstrained path usually means a constraint is missing, for example an output port with no output delay. OpenSTA reference

Hint: By default paths are listed group by group, sorted inside each group.

By default paths are listed group by group, worst first within each group. -sort_by_slack merges the groups into one list ordered by slack. OpenSTA reference

Hint: A path's group is the clock that captures it, unless `group_path` moved it.

A path's default group is the clock that captures it, so this reports paths captured by core_clock. Groups made with group_path are selected the same way. OpenSTA reference

Hint: The name says find, not report. Ask what a script would want back.

find_timing_paths takes the same selection options as report_checks but returns objects for a script. get_property reads their fields, such as slack, startpoint, and endpoint. OpenSTA reference

Hint: The N in WNS (Worst Negative Slack) is negative. Ask what it can report when nothing is negative.

WNS (Worst Negative Slack) never reports a positive number; a design that passes shows 0. report_worst_slack shows the actual worst slack, positive or negative. -min switches to hold. OpenSTA reference

Hint: The T is total. Ask what it is totalled over.

TNS (Total Negative Slack) measures how widespread the failures are, and WNS (Worst Negative Slack) how deep the worst one is. A small WNS (Worst Negative Slack) with a large TNS (Total Negative Slack) means many endpoints fail by a little. OpenSTA reference

Hint: Compare it with `report_wns`: only one of the two can report a positive number. `-min` selects hold.

report_worst_slack reports the actual value, so a passing design shows its margin. report_wns -min would show 0 for the same design. OpenSTA reference

Hint: Types means kinds of check: setup and hold, but also slew, capacitance, fanout, and pulse width.

The kinds include setup, hold, recovery, removal, clock-gating, maximum slew, capacitance, fanout, minimum pulse width, and minimum period. Each can be requested alone with its option. OpenSTA reference

Hint: A violator is any check with negative slack, not only a timing path.

This is the sign-off question in one command: is anything violated, of any kind? Timing and design-rule violations are listed together. OpenSTA reference

Hint: All three options name design rules, so the report is narrowed to those.

These are the electrical design rules, reported separately from timing slack. Reporting changes nothing; repair is a separate step. OpenSTA reference

Hint: It reports at one pin, so no path is walked. Ask which numbers exist at a pin.

Pin-level commands print numbers at one pin, without a path. They answer "how much margin is there here?" quickly, and report_checks -through then shows the path. OpenSTA reference

Hint: Arrival is when the data gets there, as opposed to when it is needed.

The arrival is when data reaches the pin. Min and max arrivals feed the hold and setup checks respectively. OpenSTA reference

Hint: Required is the limit that the arrival is compared against; slack is the difference.

For setup, data must arrive before the max required time; for hold, after the min required time. Slack is the difference between required and arrival. OpenSTA reference

Hint: Skew matters only between registers with a path between them, so ask which pairs are compared.

Skew only matters between registers connected by a timing path, so only those pairs are compared. -setup and -hold choose which check's view of skew to report. OpenSTA reference

Hint: Latency is the delay from a clock's source to where the clock is used.

With propagated clocks this is the computed delay through the built clock tree; with ideal clocks it reflects the latency set in the constraints. OpenSTA reference

Hint: Ask what the smallest period is that the paths in the design would still meet.

It also prints the matching highest frequency. It is found from the worst register-to-register paths on the same clock edge. Paths between clocks or edges, latch paths, and paths with multicycle or maximum-delay exceptions are ignored. OpenSTA reference

Hint: Properties here means how each clock was defined, not what was measured on it.

It is a quick check that the clocks were defined as intended, before any path is examined. OpenSTA reference

Hint: The name is about checking the setup of the constraints, not about setup timing.

The checks cover inputs with no input delay, outputs with no output delay, registers with no clock or several clocks, unconstrained endpoints, combinational loops, and generated clocks without a source clock. Without -verbose only counts are printed. OpenSTA reference

Hint: An endpoint is unconstrained when nothing checks it: no timing check and no output delay.

An unconstrained endpoint is never checked, so it can hide a real failure. Input ports without input delay are a separate check, -no_input_delay. OpenSTA reference

Hint: The command returns a value. Ask what a flow would do with it.

check_setup returns 1 when there are no warnings, so a flow can refuse to continue with broken constraints. OpenSTA reference

Hint: A disabled arc carries no timing at all. Ask what could have disabled one.

The reason is constraint, constant, or loop. Arcs can be disabled by set_disable_timing, by constants from case analysis, or automatically to break combinational loops. Unexpected entries often explain paths that are missing from reports. OpenSTA reference

Hint: dcalc is delay calculation: it shows the working behind one arc's delay.

It shows the inputs to the library lookup, the input slew and the output load, and the delay and slew that result. It is used to debug a delay that looks wrong. OpenSTA reference

Hint: A slew is a transition time, reported at one pin.

A slow slew at a pin slows the cells it drives. The limit it is checked against is reported by report_check_types -max_slew. OpenSTA reference

Hint: A net joins a driver to its loads and carries capacitance.

It shows the driver and the loads on the net and how much capacitance they and the wire contribute, which explains a slow driver. OpenSTA reference

Hint: An instance is one placed cell. Ask what is specific to it rather than to its cell type.

It shows how one instance is connected. The timing arcs of its cell come from report_lib_cell. OpenSTA reference

Hint: An edge is one arc of the timing graph, with a delay on it.

An edge is one arc in the timing graph, with rise and fall delays. For the calculation behind each delay, use report_dcalc. OpenSTA reference

Hint: The name includes a library, so this is about a cell definition, not a placed instance.

It shows the library definition, not the design. The name includes the library, as in NangateOpenCellLibrary/BUF_X1. OpenSTA reference

Hint: Numbers in commands and reports carry no units of their own.

Numbers in commands and reports carry no units of their own, so this is the way to confirm that 0.46 means nanoseconds and not picoseconds. OpenSTA reference

Hint: Annotation means data loaded from a file; SPEF (Standard Parasitic Exchange Format) carries parasitics.

Delays computed without parasitics on some nets are optimistic, so the coverage of the SPEF (Standard Parasitic Exchange Format) file is checked before sign-off timing is trusted. OpenSTA reference

Hint: SDF (Standard Delay Format) carries delays. Ask what this reports about them.

An SDF (Standard Delay Format) file gives delays directly instead of having them calculated. Arcs to and from top-level ports are included only with -from_in_ports and -to_out_ports. OpenSTA reference

Hint: The same idea as the delay report, but for timing checks rather than delays.

Timing checks (setup, hold, recovery, removal) can be annotated from an SDF (Standard Delay Format) file separately from delays, so their coverage is reported separately. OpenSTA reference

Hint: Activity is how often pins switch, which is what a power calculation needs.

Activity comes from simulation (read_vcd, read_saif) or from set_power_activity. Power depends on how often nets switch. Without annotated activity, default input activity is propagated, which is only an estimate. OpenSTA reference

Hint: Power splits into internal, switching, and leakage, reported per kind of cell.

The groups are sequential, combinational, clock, macro, and pad, in watts. Without simulation activity, an input activity of 0.1 and duty of 0.5 are assumed and propagated through the logic. OpenSTA reference

Startpoint: dpath.b_reg.out[4]$_DFFE_PP_
            (rising edge-triggered flip-flop clocked by core_clock)
Endpoint: dpath.b_reg.out[4]$_DFFE_PP_
          (rising edge-triggered flip-flop clocked by core_clock)
Path Group: core_clock
Path Type: min
   ...
   0.00    0.00   clock core_clock (rise edge)
   0.07    0.07   clock network delay (propagated)
   0.15    0.22   clock uncertainty
   0.00    0.22   clock reconvergence pessimism
           0.22 ^ dpath.b_reg.out[4]$_DFFE_PP_/CK (DFF_X1)
   0.00    0.22   library hold time
           0.22   data required time
---------------------------------------------------------
           0.22   data required time
          -0.19   data arrival time
---------------------------------------------------------
          -0.04   slack (VIOLATED)

Hint: Look at the Path Type line, and at which library time the capture side uses.

Path Type: max is a setup check and Path Type: min a hold check. The capture side confirms it: a setup report subtracts library setup time, a hold report adds library hold time. A path from a register back to itself is common in hold reports. OpenSTA reference

   0.38    0.38   clock core_clock (rise edge)
   0.07    0.45   clock network delay (propagated)
   0.00    0.45   clock reconvergence pessimism
           0.45 ^ dpath.a_reg.out[9]$_DFFE_PP_/CK (DFF_X1)
  -0.03    0.42   library setup time
           0.42   data required time
---------------------------------------------------------
           0.42   data required time
          -0.48   data arrival time
---------------------------------------------------------
          -0.06   slack (VIOLATED)

Hint: The two lines just above the final rule are the two numbers being compared.

Setup slack is required minus arrival: the data must arrive before the required time, so a later arrival gives a negative slack. For a hold check the order reverses, arrival minus required. OpenSTA reference

   0.38    0.38   clock core_clock (rise edge)
   0.07    0.45   clock network delay (propagated)
   0.00    0.45   clock reconvergence pessimism
           0.45 ^ dpath.a_reg.out[9]$_DFFE_PP_/CK (DFF_X1)
  -0.03    0.42   library setup time
           0.42   data required time

Hint: Follow the capture side down: the edge time, then the clock tree, then the library time.

The capture edge occurs at 0.38 at the clock source, but it arrives at the register's clock pin through the clock tree, 0.07 later, at 0.45. The data must arrive the setup time before that: 0.45 minus 0.03 is 0.42. OpenSTA reference

   0.00    0.00   clock core_clock (rise edge)
   0.07    0.07   clock network delay (propagated)
   0.00    0.07 ^ dpath.a_reg.out[2]$_DFFE_PP_/CK (DFF_X1)
   0.10    0.17 ^ dpath.a_reg.out[2]$_DFFE_PP_/Q (DFF_X1)
   ...
   0.38    0.38   clock core_clock (rise edge)
   0.07    0.45   clock network delay (propagated)
   0.00    0.45   clock reconvergence pessimism
           0.45 ^ dpath.a_reg.out[9]$_DFFE_PP_/CK (DFF_X1)

Hint: Compare the launch side and the capture side line by line.

The launch side adds 0.07 to the arrival and the capture side adds 0.07 to the required time, so the two cancel. (propagated) means the delay was computed through the built clock tree; an estimate would read (ideal). OpenSTA reference

Fanout     Cap    Slew   Delay    Time   Description
-----------------------------------------------------------------------------
                          0.00    0.00   clock core_clock (rise edge)
                          0.07    0.07   clock network delay (propagated)
                  0.01    0.00    0.07 ^ dpath.a_reg.out[2]$_DFFE_PP_/CK (DFF_X1)
     4    7.49    0.02    0.10    0.17 ^ dpath.a_reg.out[2]$_DFFE_PP_/Q (DFF_X1)
     3    6.51    0.02    0.03    0.20 v _520_/ZN (NAND2_X1)
     1    2.04    0.01    0.02    0.22 ^ _551_/ZN (NAND2_X1)
     2    3.48    0.01    0.02    0.24 v _553_/ZN (NAND2_X1)
     1    5.86    0.01    0.03    0.27 v place79/Z (BUF_X1)
     2    7.97    0.01    0.02    0.29 ^ _554_/ZN (NAND2_X4)
     1    5.90    0.01    0.01    0.30 v _722_/ZN (NAND2_X4)
     2    8.76    0.01    0.01    0.32 ^ _724_/ZN (NAND2_X4)
    14   35.04    0.02    0.03    0.34 v _755_/ZN (NAND2_X4)
    16   35.73    0.05    0.07    0.41 ^ _854_/ZN (AOI21_X4)
     1    2.51    0.02    0.03    0.44 v _891_/ZN (NAND2_X1)
     1    1.71    0.01    0.02    0.46 ^ _894_/ZN (NAND3_X1)
     1    1.72    0.01    0.01    0.47 v _896_/ZN (NAND2_X1)
     1    1.44    0.01    0.01    0.48 ^ _897_/ZN (INV_X1)
                  0.01    0.00    0.48 ^ dpath.a_reg.out[9]$_DFFE_PP_/D (DFF_X1)
                                  0.48   data arrival time

Hint: The Delay column is per stage, and the Cap and Fanout columns say why a stage is slow.

The Delay column shows each stage's contribution, and the Cap and Fanout columns explain it: _854_ drives the largest load in the path, and its output slew of 0.05 is also the slowest, which slows the next stage. Capacitance here is in femtofarads, the unit this library uses. OpenSTA reference

   0.00    0.00   clock core_clock (rise edge)
   0.07    0.07   clock network delay (propagated)
   0.00    0.07 ^ dpath.b_reg.out[4]$_DFFE_PP_/CK (DFF_X1)
   0.09    0.16 v dpath.b_reg.out[4]$_DFFE_PP_/Q (DFF_X1)
   0.02    0.18 ^ _825_/ZN (INV_X1)
   0.01    0.19 v _826_/ZN (OAI21_X2)
   0.00    0.19 v dpath.b_reg.out[4]$_DFFE_PP_/D (DFF_X1)
           0.19   data arrival time

   0.00    0.00   clock core_clock (rise edge)
   0.07    0.07   clock network delay (propagated)
   0.15    0.22   clock uncertainty
   0.00    0.22   clock reconvergence pessimism
           0.22 ^ dpath.b_reg.out[4]$_DFFE_PP_/CK (DFF_X1)
   0.00    0.22   library hold time
           0.22   data required time
---------------------------------------------------------
           0.22   data required time
          -0.19   data arrival time
---------------------------------------------------------
          -0.04   slack (VIOLATED)

Hint: Work out what the required time would be without the extra line in the middle.

For hold, the data must arrive after the required time. Without uncertainty the required time would be 0.07 and the check would pass; the 0.15 of hold uncertainty moves it to 0.22. A hold violation is fixed by adding delay to the data path, not by speeding it up. OpenSTA reference

   0.00    0.00   clock core_clock (rise edge)
   0.07    0.07   clock network delay (propagated)
   0.15    0.22   clock uncertainty
   0.00    0.22   clock reconvergence pessimism
           0.22 ^ dpath.b_reg.out[4]$_DFFE_PP_/CK (DFF_X1)
   0.00    0.22   library hold time
           0.22   data required time

Hint: CRPR (Clock Reconvergence Pessimism Removal) credits back pessimism on the shared clock path. Ask what would create pessimism in the first place.

CRPR (Clock Reconvergence Pessimism Removal) credits back the difference between late and early delay on the part of the clock tree that launch and capture share, since one buffer cannot be early and late at once. With no derating or variation in this run, early and late delays are equal and the credit is 0. OpenSTA reference

% report_checks -format end -group_path_count 6
max_delay/setup group core_clock

                                     Required  Actual
Endpoint                               Delay   Delay   Slack
------------------------------------------------------------
dpath.a_reg.out[9]$_DFFE_PP_/D (DFF_X1)    0.42    0.48   -0.06 (VIOLATED)
dpath.a_reg.out[4]$_DFFE_PP_/D (DFF_X1)    0.42    0.48   -0.06 (VIOLATED)
dpath.a_reg.out[8]$_DFFE_PP_/D (DFF_X1)    0.42    0.48   -0.06 (VIOLATED)
dpath.a_reg.out[10]$_DFFE_PP_/D (DFF_X1)    0.42    0.48   -0.06 (VIOLATED)
dpath.a_reg.out[6]$_DFFE_PP_/D (DFF_X1)    0.42    0.48   -0.06 (VIOLATED)
dpath.a_reg.out[0]$_DFFE_PP_/D (DFF_X1)    0.42    0.48   -0.06 (VIOLATED)

max_delay/setup group vclk_core_clock

                                     Required  Actual
Endpoint                               Delay   Delay   Slack
------------------------------------------------------------
resp_msg[14] (output)                   0.36    0.42   -0.06 (VIOLATED)
resp_msg[13] (output)                   0.36    0.42   -0.06 (VIOLATED)
resp_msg[11] (output)                   0.36    0.42   -0.06 (VIOLATED)
resp_msg[12] (output)                   0.36    0.42   -0.06 (VIOLATED)
resp_msg[9] (output)                    0.36    0.41   -0.05 (VIOLATED)
resp_msg[15] (output)                   0.36    0.41   -0.05 (VIOLATED)

Hint: Look at the command line at the top: something there limits how many rows appear.

-group_path_count 6 limits the list to 6 per group, so it cannot show how many fail in total. report_tns, or -slack_max 0 with a large count, answers that. OpenSTA reference

% report_wns
wns max -0.06

% report_tns
tns max -2.18

Hint: One number is the worst single failure and the other is a sum. Divide one by the other.

WNS (Worst Negative Slack) is the deepest failure and TNS (Total Negative Slack) the sum over failing endpoints. No endpoint fails by more than 0.06, so a total of 2.18 needs at least 2.18 / 0.06, about 37, failing endpoints. Both lines say max, so these are setup numbers. OpenSTA reference

% check_setup -verbose
Warning: There is 1 input port missing set_input_delay.
  req_msg[5]
Warning: There are 18 output ports missing set_output_delay.
  req_rdy
  resp_msg[0]
  resp_msg[10]
   ...
  resp_val
Warning: There are 18 unconstrained endpoints.
  req_rdy
  resp_msg[0]

Hint: These are warnings about missing constraints, not about failing timing.

Ports with no input or output delay are not timed, so their paths never appear in slack reports; a clean report_wns can hide them. The 18 unconstrained endpoints are the same 18 output ports. OpenSTA reference

% report_check_types
Group                                  Slack
--------------------------------------------
core_clock                             -0.04
vclk_core_clock                         0.22
core_clock                             -0.06
vclk_core_clock                        -0.06

Hint: Compare the four slack values with the worst hold and worst setup slack from the path reports.

The table has no labels, so compare it with the path reports: -0.04 is the worst hold slack from report_checks -path_delay min, and -0.06 is the worst setup slack. Min (hold) is printed first, then max (setup). OpenSTA reference

% report_clock_skew
Clock core_clock
   0.07 source latency dpath.a_reg.out[12]$_DFFE_PP_/CK ^
  -0.07 target latency dpath.b_reg.out[9]$_DFFE_PP_/CK ^
   0.00 CRPR
--------------
  -0.00 setup skew

Clock vclk_core_clock
No launch/capture paths found.

Hint: Skew is a difference. Look at the two latency lines and at what sits between them.

Skew is the target latency minus the source latency, adjusted by CRPR (Clock Reconvergence Pessimism Removal). The virtual clock reaches no registers, so it has no register pairs to compare, which is normal. OpenSTA reference

% report_clock_min_period
core_clock period_min = 0.44 fmax = 2267.21
vclk_core_clock period_min = 0.00 fmax = inf

Hint: Compare the period reported here with the 0.38 ns the clock was given.

The minimum period comes from the worst same-edge register-to-register paths. fmax is its inverse, in megahertz: 1 / 0.441 ns is about 2267 MHz (megahertz). The virtual clock has no register paths, so it shows 0 and infinity. OpenSTA reference

% report_parasitic_annotation
Found 22 unannotated drivers.
Found 0 partially unannotated drivers.

Hint: Annotation comes from the parasitics file, so ask what those 22 drivers are missing.

These nets got nothing from the SPEF (Standard Parasitic Exchange Format) file. A net without parasitics is timed with pin capacitance only, which is optimistic. -report_unannotated lists the nets, so they can be checked before the timing is trusted. OpenSTA reference

(core_clock ^) r 0.15:0.02 f 0.15:0.04
(vclk_core_clock ^) r 0.16:0.26 f 0.18:0.24

Hint: Each pair is two numbers separated by a colon: min first, then max.

r and f are rising and falling data; each gives min:max slack. Min is the hold check and max the setup check, so rising data has 0.15 of hold slack and 0.02 of setup slack, matching the 0.02 in the path report for this endpoint. OpenSTA reference

Hint: Three things are named. Ask what each one contributes to an analysis.

The mode brings the constraints, the library the cell timing, and the SPEF (Standard Parasitic Exchange Format) file the wires. A design is signed off at several such combinations: each pairs an operating condition (the library and parasitics) with a mode (the constraints that apply in it). A scene names one such combination, so reports can cover several at once. Scenes are defined after the libraries and parasitics are read. OpenSTA reference

Hint: The same clock is created twice with different periods. Ask why that is not a conflict.

A chip is constrained differently in different modes: functional, scan shift, at-speed test. Modes keep those constraint sets apart, and a scene then says which mode is analysed with which library. Creating the first mode removes the default one. OpenSTA reference

Hint: Ask what the commands typed after it now refer to.

Reporting commands work on the current scene unless -scenes names others. Switching scenes is how one session compares the same path at the slow and the fast condition. get_scenes lists what is defined. OpenSTA reference

Hint: Ask what the report covers that the current scene alone would not.

Most reporting commands take -scenes, and the default is every scene. Sign-off timing is the worst result across all of them, since setup usually fails slow and hold fails fast. OpenSTA reference

Hint: Check whether this is the current way to do it.

It is kept so older scripts still run, and it is used before read_liberty, which is what distinguishes it. New flows use define_scene, which ties a mode, a library, and parasitics together rather than naming a corner alone. OpenSTA reference

Hint: Ask what a mode can have several of.

One mode is usually paired with several operating conditions, so a script iterates the scenes of a mode to report each. Like the other object-access commands, it accepts -filter. OpenSTA reference

Hint: Between the full path and one line per end, there is a middle.

summary keeps the start point, which end drops, and omits the required and arrival columns that end shows. It is the quickest way to see which registers the failing paths run between. OpenSTA reference

Hint: Ask what remains when the stages and the numbers are both dropped.

What is left is the start point, end point, path group, and path type. That alone answers which paths would be reported, which is how a selection is checked before a long report is run. Confirm it by reading the header lines: the path type says whether it is a setup or a hold path. OpenSTA reference

Hint: Ask who reads this one.

A script that post-processes timing should not parse the human report, whose layout changes between versions. The JSON (JavaScript Object Notation) form is stable, and -fields is ignored because every field is present. OpenSTA reference

Hint: Three separate checks are named. Ask what running all of them at once would take.

With no keywords every check runs: missing input and output delays, registers with no clock or several clocks, unconstrained endpoints, combinational loops, and generated clocks whose source is not a clock. Naming a few narrows a long run, or focuses a script on what it cares about. OpenSTA reference

Hint: One of these reports zero as soon as nothing is failing.

Worst negative slack is clamped at zero, so a design that closes reports the same number however much margin it has. The worst slack keeps counting upward, which is what makes it the better number to plot across runs. OpenSTA reference

Hint: Two of these describe the clock network, but only one compares two ends of a path.

Latency is how long the clock takes to reach one register, which largely cancels within a clock. Skew is the difference between two of them on the same path, which does not cancel and is what eats the budget. OpenSTA reference

Hint: The others report timing; this one reports whether timing means anything.

A design with half its registers unclocked reports beautiful timing, because nothing is checked. This is the command that says so, and it is the first thing to run on a new constraints file. Listing unconstrained paths is useful too, but it answers a narrower question. OpenSTA reference

Hint: The report wanted here is the hold report.

Minimum delay paths are the hold checks and maximum delay paths the setup checks, and min_max asks for both. Other timers spell the same option -delay_type, which is why a script moved between tools trips here rather than anywhere more interesting. OpenSTA reference

Hint: Two of these show the clock. Only one expands it cell by cell.

The plain full format shows the data path with the clock arrival as a single number. Adding the clock shows the clock edges, and expanding it shows every buffer in the tree, which is what you need when the skew itself is the suspect. OpenSTA reference

Hint: The other counting option limits how many paths may share one endpoint.

By default one path is reported per endpoint and a handful per group. Raising the group count gives a longer list of the worst paths; raising the endpoint count gives several paths through the same endpoint, which is what you want when one register is failing for more than one reason. OpenSTA reference